Playing HTML5 video on fullscreen in android webview. Note: I did not write this, it has been taken from http://stackoverflow.com/questions/15768837/playing-html5-video-on-fullscreen-in-android-webview

VideoEnabledWebChromeClient.java

import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.media.MediaPlayer.OnErrorListener;
import android.media.MediaPlayer.OnPreparedListener;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.webkit.WebChromeClient;
import android.widget.FrameLayout;
import android.widget.VideoView;

/**
 * This class serves as a WebChromeClient to be set to a WebView, allowing it to play video.
 * It works with old VideoView-s as well as the new HTML5VideoFullScreen inner classes.
 * With VideoView (typically API level <11), it will always show full-screen.
 * With HTML5VideoFullScreen (typically API level 11+), it will show both in-page and full-screen.
 * 
 * IMPORTANT NOTES:
 * - For API level 11+, android:hardwareAccelerated="true" must be set in the application manifest.
 * - The invoking activity must call VideoEnabledWebChromeClient's onBackPressed() inside of its own onBackPressed().
 * - Tested in Android API level 8+. Only tested on http://m.youtube.com.
 *
 * @author Cristian Perez (http://cpr.name)
 *
 */
public class VideoEnabledWebChromeClient extends WebChromeClient implements OnPreparedListener, OnCompletionListener, OnErrorListener
{
    public interface ToggledFullscreenCallback
    {
        public void toggledFullscreen(boolean fullscreen);
    }

    private View activityNonVideoView;
    private ViewGroup activityVideoView;
    private View loadingView;
    private VideoEnabledWebView webView;

    private boolean isVideoFullscreen; // Indicates if the video is being displayed using a custom view (typically full-screen)
    private FrameLayout videoViewContainer;
    private CustomViewCallback videoViewCallback;

    private ToggledFullscreenCallback toggledFullscreenCallback;

    /**
     * Never use this constructor alone.
     * This constructor allows this class to be defined as an inline inner class in which the user can override methods
     */
    public VideoEnabledWebChromeClient()
    {
    }

    /**
     * Builds a video enabled WebChromeClient.
     * @param activityNonVideoView A View in the activity's layout that contains every other view that should be hidden when the video goes full-screen.
     * @param activityVideoView A ViewGroup in the activity's layout that will display the video. Typically you would like this to fill the whole layout.
     */
    public VideoEnabledWebChromeClient(View activityNonVideoView, ViewGroup activityVideoView)
    {
        this.activityNonVideoView = activityNonVideoView;
        this.activityVideoView = activityVideoView;
        this.loadingView = null;
        this.webView = null;
        this.isVideoFullscreen = false;
    }

    /**
     * Builds a video enabled WebChromeClient.
     * @param activityNonVideoView A View in the activity's layout that contains every other view that should be hidden when the video goes full-screen.
     * @param activityVideoView A ViewGroup in the activity's layout that will display the video. Typically you would like this to fill the whole layout.
     * @param loadingView A View to be shown while the video is loading (typically only used in API level <11). Must be already inflated and without a parent view.
     */
    public VideoEnabledWebChromeClient(View activityNonVideoView, ViewGroup activityVideoView, View loadingView)
    {
        this.activityNonVideoView = activityNonVideoView;
        this.activityVideoView = activityVideoView;
        this.loadingView = loadingView;
        this.webView = null;
        this.isVideoFullscreen = false;
    }

    /**
     * Builds a video enabled WebChromeClient.
     * @param activityNonVideoView A View in the activity's layout that contains every other view that should be hidden when the video goes full-screen.
     * @param activityVideoView A ViewGroup in the activity's layout that will display the video. Typically you would like this to fill the whole layout.
     * @param loadingView A View to be shown while the video is loading (typically only used in API level <11). Must be already inflated and without a parent view.
     * @param webView The owner VideoEnabledWebView. Passing it will enable the VideoEnabledWebChromeClient to detect the HTML5 video ended event and exit full-screen.
     * Note: The web page must only contain one video tag in order for the HTML5 video ended event to work. This could be improved if needed (see Javascript code).
     */
    public VideoEnabledWebChromeClient(View activityNonVideoView, ViewGroup activityVideoView, View loadingView, VideoEnabledWebView webView)
    {
        this.activityNonVideoView = activityNonVideoView;
        this.activityVideoView = activityVideoView;
        this.loadingView = loadingView;
        this.webView = webView;
        this.isVideoFullscreen = false;
    }

    /**
     * Indicates if the video is being displayed using a custom view (typically full-screen)
     * @return true it the video is being displayed using a custom view (typically full-screen)
     */
    public boolean isVideoFullscreen()
    {
        return isVideoFullscreen;
    }

    /**
     * Set a callback that will be fired when the video starts or finishes displaying using a custom view (typically full-screen)
     * @param callback A VideoEnabledWebChromeClient.ToggledFullscreenCallback callback
     */
    public void setOnToggledFullscreen(ToggledFullscreenCallback callback)
    {
        this.toggledFullscreenCallback = callback;
    }

    @Override
    public void onShowCustomView(View view, CustomViewCallback callback)
    {
        if (view instanceof FrameLayout)
        {
            // A video wants to be shown
            FrameLayout frameLayout = (FrameLayout) view;
            View focusedChild = frameLayout.getFocusedChild();

            // Save video related variables
            this.isVideoFullscreen = true;
            this.videoViewContainer = frameLayout;
            this.videoViewCallback = callback;

            // Hide the non-video view, add the video view, and show it
            activityNonVideoView.setVisibility(View.INVISIBLE);
            activityVideoView.addView(videoViewContainer, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
            activityVideoView.setVisibility(View.VISIBLE);

            if (focusedChild instanceof VideoView)
            {
                // VideoView (typically API level <11)
                VideoView videoView = (VideoView) focusedChild;
                // Handle all the required events
                videoView.setOnPreparedListener(this);
                videoView.setOnCompletionListener(this);
                videoView.setOnErrorListener(this);
            }
            else // Usually android.webkit.HTML5VideoFullScreen$VideoSurfaceView, sometimes android.webkit.HTML5VideoFullScreen$VideoTextureView
            {
                // HTML5VideoFullScreen (typically API level 11+)
                // Handle HTML5 video ended event
                if (webView != null && webView.getSettings().getJavaScriptEnabled())
                {
                    // Run javascript code that detects the video end and notifies the interface
                    String js = "javascript:";
                    js += "_ytrp_html5_video = document.getElementsByTagName('video')[0];";
                    js += "if (_ytrp_html5_video !== undefined) {";
                    {
                        js += "function _ytrp_html5_video_ended() {";
                        {
                            js += "_ytrp_html5_video.removeEventListener('ended', _ytrp_html5_video_ended);";
                            js += "_VideoEnabledWebView.notifyVideoEnd();"; // Must match Javascript interface name and method of VideoEnableWebView
                        }
                        js += "}";
                        js += "_ytrp_html5_video.addEventListener('ended', _ytrp_html5_video_ended);";
                    }
                    js += "}";
                    webView.loadUrl(js);
                }
            }

            // Notify full-screen change
            if (toggledFullscreenCallback != null)
            {
                toggledFullscreenCallback.toggledFullscreen(true);
            }
        }
    }

    @Override
    public void onShowCustomView(View view, int requestedOrientation, CustomViewCallback callback) // Only available in API level 14+
    {
        onShowCustomView(view, callback);
    }

    @Override
    public void onHideCustomView()
    {
        // This method must be manually (internally) called on video end in the case of VideoView (typically API level <11)
        // This method must be manually (internally) called on video end in the case of HTML5VideoFullScreen (typically API level 11+) because it's not always called automatically
        // This method must be manually (internally) called on back key press (from this class' onBackPressed() method)

        if (isVideoFullscreen)
        {
            // Hide the video view, remove it, and show the non-video view
            activityVideoView.setVisibility(View.INVISIBLE);
            activityVideoView.removeView(videoViewContainer);
            activityNonVideoView.setVisibility(View.VISIBLE);

            // Call back
            if (videoViewCallback != null) videoViewCallback.onCustomViewHidden();

            // Reset video related variables
            isVideoFullscreen = false;
            videoViewContainer = null;
            videoViewCallback = null;

            // Notify full-screen change
            if (toggledFullscreenCallback != null)
            {
                toggledFullscreenCallback.toggledFullscreen(false);
            }
        }
    }

    @Override
    public View getVideoLoadingProgressView() // Video will start loading, only called in the case of VideoView (typically API level <11)
    {
        if (loadingView != null)
        {
            loadingView.setVisibility(View.VISIBLE);
            return loadingView;
        }
        else
        {
            return super.getVideoLoadingProgressView();
        }
    }

    @Override
    public void onPrepared(MediaPlayer mp) // Video will start playing, only called in the case of VideoView (typically API level <11)
    {
        if (loadingView != null)
        {
            loadingView.setVisibility(View.GONE);
        }
    }

    @Override
    public void onCompletion(MediaPlayer mp) // Video finished playing, only called in the case of VideoView (typically API level <11)
    {
        onHideCustomView();
    }

    @Override
    public boolean onError(MediaPlayer mp, int what, int extra) // Error while playing video, only called in the case of VideoView (typically API level <11)
    {
        return false; // By returning false, onCompletion() will be called
    }

    /**
     * Notifies the class that the back key has been pressed by the user.
     * This must be called from the Activity's onBackPressed(), and if it returns false, the activity itself should handle it. Otherwise don't do anything.
     * @return Returns true if the event was handled, and false if it is not (video view is not visible)
     */
    public boolean onBackPressed()
    {
        if (isVideoFullscreen)
        {
            onHideCustomView();
            return true;
        }
        else
        {
            return false;
        }
    }

}

VideoEnabledWebView.java

import java.util.Map;

import android.annotation.SuppressLint;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.util.AttributeSet;
import android.webkit.JavascriptInterface;
import android.webkit.WebChromeClient;
import android.webkit.WebView;

/**
 * This class serves as a WebView to be used in conjunction with a VideoEnabledWebChromeClient.
 * It makes it possible to detect the HTML5 video ended event so that the VideoEnabledWebChromeClient can exit full-screen.
 * 
 * IMPORTANT NOTES:
 * - Javascript is enabled by default and must not be disabled with getSettings().setJavaScriptEnabled(false).
 * - setWebChromeClient() must be called before any loadData(), loadDataWithBaseURL() or loadUrl() method.
 *
 * @author Cristian Perez (http://cpr.name)
 *
 */
public class VideoEnabledWebView extends WebView
{
    public interface ToggledFullscreenCallback
    {
        public void toggledFullscreen(boolean fullscreen);
    }

    private VideoEnabledWebChromeClient videoEnabledWebChromeClient;
    private boolean addedJavascriptInterface;

    public VideoEnabledWebView(Context context)
    {
        super(context);
        addedJavascriptInterface = false;
    }

    public VideoEnabledWebView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        addedJavascriptInterface = false;
    }

    public VideoEnabledWebView(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        addedJavascriptInterface = false;
    }

    /**
     * Pass only a VideoEnabledWebChromeClient instance.
     */
    @Override @SuppressLint("SetJavaScriptEnabled")
    public void setWebChromeClient(WebChromeClient client)
    {
        getSettings().setJavaScriptEnabled(true);

        if (client instanceof VideoEnabledWebChromeClient)
        {
            this.videoEnabledWebChromeClient = (VideoEnabledWebChromeClient) client;
        }

        super.setWebChromeClient(client);
    }

    @Override
    public void loadData(String data, String mimeType, String encoding)
    {
        addJavascriptInterface();
        super.loadData(data, mimeType, encoding);
    }

    @Override
    public void loadDataWithBaseURL(String baseUrl, String data, String mimeType, String encoding, String historyUrl)
    {
        addJavascriptInterface();
        super.loadDataWithBaseURL(baseUrl, data, mimeType, encoding, historyUrl);
    }

    @Override
    public void loadUrl(String url)
    {
        addJavascriptInterface();
        super.loadUrl(url);
    }

    @Override
    public void loadUrl(String url, Map<String, String> additionalHttpHeaders)
    {
        addJavascriptInterface();
        super.loadUrl(url, additionalHttpHeaders);
    }

    private void addJavascriptInterface()
    {
        if (!addedJavascriptInterface)
        {
            // Add javascript interface to be called when the video ends (must be done before page load)
            addJavascriptInterface(new Object()
            {
                @JavascriptInterface @SuppressWarnings("unused")
                public void notifyVideoEnd() // Must match Javascript interface method of VideoEnabledWebChromeClient
                {
                    // This code is not executed in the UI thread, so we must force it to happen
                    new Handler(Looper.getMainLooper()).post(new Runnable()
                    {
                        @Override
                        public void run()
                        {
                            if (videoEnabledWebChromeClient != null)
                            {
                                videoEnabledWebChromeClient.onHideCustomView();
                            }
                        }
                    });
                }
            }, "_VideoEnabledWebView"); // Must match Javascript interface name of VideoEnabledWebChromeClient

            addedJavascriptInterface = true;
        }
    }

}