title: Mobile youtube video and its HTML5 player
body: <p>I am trying to open m.youtube.com using an ordinary browser but to be able to play the videos using HTML5 (instead of the default RTSP playback). To do that, I spoofed User-Agent in Firefox, and added there a string corresponding to iPhone's Safari UserAgent string. After I've done that, I see a nice "iPhone-like" version of the Youtube (instead of an ordinary m.youtube.com for other mobile devices). But the video, when selected, is not being played (on a "User-Agent-spoofed" Safari i can hear only sound, on "spoofed" Firefox the video is hung with a spinning "video is loading" icon). Why that might happen? what kind of features of Safari for iOS HTML5 version of youtube site may use that the video is not played in desktop Safari and Mozilla?</p>
  
  <p>I have checked the Desktop browser requests and responses with Wiresharked, and found the GET request which corresponds to the video asked (the request's Content-type is video/mp4). But the playback works always only on the iPhone's Safari.</p>
  
  <p>What may be the reason? I tried to look into HTML5 code of the Youtube page that contains video player, but there's so much JavaScript (most of HTML is being generated dynamically) that I got lost in it.</p>
  
  <p>Is there any way to make it work on ordinary browsers (I can modify the requests/cookies on-the-fly)? I'd like to have an iPhone-styled youtube with HTML5 on my desktop browser.</p>
  
  <p>Thank you</p>