Minimal VideoView

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="16dp"
    android:orientation="vertical"
    tools:context="com.example.myapplication.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />

    <VideoView
        android:id="@+id/a_main_video"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

AndroidManifest.xml

    <uses-permission android:name="android.permission.INTERNET" />

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private static final String VIDEO_URL = "http://techslides.com/demos/sample-videos/small.mp4";

    private VideoView videoView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        videoView = (VideoView) findViewById(R.id.a_main_video);
        videoView.setVideoURI(Uri.parse(VIDEO_URL));
        videoView.start();
    }
}