javascript:var%20video_id=null;var%20video_hash=null;var%20video_player=document.getElementById('movie_player');if(video_player){var%20flash_variables=video_player.attributes.getNamedItem('flashvars');if(flash_variables){var%20flash_values=flash_variables.value;if(flash_values){var%20video_id_match=flash_values.match(/[^a-z]video_id=([^(&|$)]*)/);if(video_id_match!=null)video_id=video_id_match[1];var%20video_hash_match=flash_values.match(/[^a-z]t=([^(&|$)]*)/);if(video_hash_match!=null)video_hash=video_hash_match[1]}}}if(video_id==null||video_hash==null){var%20args=null;try{args=yt.getConfig('SWF_ARGS')}catch(e){}if(args){video_id=args['video_id'];video_hash=args['t']}}if(video_id!=null&&video_hash!=null){var%20fmt='18';try{if(yt.getConfig('IS_HD_AVAILABLE'))fmt='22'}catch(e){}if(!document.getElementById('download-youtube-video')){var%20yt_mp4_path='http://www.youtube.com/get_video?fmt='+fmt+'&video_id='+video_id+'&t='+video_hash;var%20div_embed=document.getElementById('watch-embed-div');if(div_embed){var%20div_download=document.createElement('div');div_download.innerHTML='%3Cbr%20/%3E%20%3Cspan%20id='download-youtube-video'%3E%20%3Ca%20href=''+yt_mp4_path+''%20onclick='blur(this);'%3EDownload%20as%20MP4%3C/a%3E%3C/span%3E';div_embed.appendChild(div_download);}if(navigator.appName!='Microsoft%20Internet%20Explorer'){document.location.href='http://www.youtube.com/get_video?fmt='+fmt+'&video_id='+video_id+'&t='+video_hash}}}void(0);
Try this code