Cách download film trong youtube.com

javascript:if%20(document.getElementById(`download-youtube-video`)==null%20&&%20!!(document.location.href.match(/http://[a-zA-Z.]*youtube.com/watch/)))%20{var%20yt_mp4_path=`http://www.youtube.com/get_video?fmt=18&video_id=`+swfArgs[`video_id`]+`&t=`+swfArgs[`t`];%20var%20div_embed=document.getElementById(`watch-embed-div`);div_embed.innerHTML=div_embed.innerHTML+`%20Tai phim dinh dang MP4%20`+%20%20((navigator.userAgent.indexOf(`Safari`)!=-1)?`(control-click%20and%20select%20Download%20linked%20file%20as)`:(`(Bam chuot phai va chon%20Save%20`+%20(navigator.appName==`Microsoft%20Internet%20Explorer`?`target`:`link`)%20+`%20as)`))+``;}void(0);