title: HTML5 <video>: Recording both audio and video
body: <p>I'm struggling to record both video and audio to a single file format (such as mp4). From all the examples I find on the web, getUserMedia can only record sound or video, to 2 different files.<br>
  I even managed to record both a video file (webm) and an audio file (.wav), but now I cannot use the <code>&lt;video&gt;</code> element to play them both, since it can only accept one valid source. 
  I tried merging the 2 files, but there is no sync.</p>
  
  <p>Can anyone please provide an example how to record BOTH audio and video on the same .record function ?</p>
  
  <p>Thanks !</p>