Download YouTube Videos as MP4

// ==UserScript==// @name           Download YouTube Videos as MP4// @description    Adds an option to download YouTube videos.// @description    http://userscripts.org/scripts/show/25105// @description    http://userscripts.org/scripts/source/25105.user.js// @namespace      http://googlesystem.blogspot.com// @include        http://*.youtube.com/watch?*// @include        http://youtube.com/watch?*// @version        0.6// ==/UserScript==(function () {  if (document.getElementById('download-youtube-video')) return;  var video_id = null;  var video_hash = null;  var video_player = document.getElementById('movie_player');    if (video_player) {    var flash_variables = video_player.attributes.getNamedItem('flashvars');      if (flash_variables) {      var flash_values = flash_variables.value;      if (flash_values) {        var video_id_match = flash_values.match(/[^a-z]video_id=([^(\&|$)]*)/);        if (video_id_match!=null) video_id = video_id_match[1];        var video_hash_match = flash_values.match(/[^a-z]t=([^(\&|$)]*)/);        if (video_hash_match!=null) video_hash = video_hash_match[1];              }    }  }    if (video_id==null || video_hash==null) {    var args = unsafeWindow.swfArgs;    if (args) {      video_id = args['video_id'];      video_hash = args['t'];      }  }    if (video_id==null || video_hash==null) return;    var yt_mp4_path ='http://www.youtube.com/get_video?fmt=18&amp;video_id='+video_id+'&amp;t='+video_hash;    var div_embed = document.getElementById('watch-embed-div');   if (div_embed) {           var div_download = document.createElement('div');     div_download.innerHTML = '<br /> <span id=\'download-youtube-video\'> <a href=\''+yt_mp4_path+'\' onclick=\'blur(this);\'>Download as MP4</a></span>';     div_embed.appendChild(div_download);  }  if (video_id==null || video_hash==null) return;    var yt_mp4_path_hd ='http://www.youtube.com/get_video?fmt=22&amp;video_id='+video_id+'&amp;t='+video_hash;    var div_embed = document.getElementById('watch-embed-div');   if (div_embed) {           var div_download = document.createElement('div');     div_download.innerHTML = '<br /> <span id=\'download-youtube-video\'> <a href=\''+yt_mp4_path_hd+'\' onclick=\'blur(this);\'>Download as MP4 HD</a></span>';     div_embed.appendChild(div_download);  }})();