flash-yt-embed-videos-to-html5.user.js

// ==UserScript==
// @name         Flash youtube videos to HTML5
// @namespace    http://howl.moe/
// @version      0.1
// @description  fuck flash with a fucking huge cactus. It goddamn sucks and should die in a fire.
// @author       Howl
// @match        *://*/*
// @grant        none
// ==/UserScript==

var re = /^https?:\/\/(?:www.)?youtube.com\/v\/([^?&]+).*$/i;
var a = document.getElementsByTagName("object");
for (var b = 0; b < a.length; b++) {
    for (var c = 0; c < a[b].children.length; c++) {
        if (a[b].children[c].tagName == "EMBED") {
            if (re.test(a[b].children[c].src)) {
                vid = re.exec(a[b].children[c].src)[1];
                frame = document.createElement("iframe");
                frame.src = "https://www.youtube.com/embed/" + vid;
                frame.width = (a[b].width != "" ? a[b].width : 600);
                frame.height = (a[b].height != "" ? a[b].height : 600);
                frame.frameBorder = 0;
                frame.allowFullscreen = true;
                a[b].parentNode.replaceChild(frame, a[b]);
            }
        }
    }
}