title: MP4 video runs slow in videojs player in Firefox and IE but not Chrome
body: <p>Anyone know why that would be? I've googled but no one seems to have had the same problem.
  The FF version is 30.0 for Windows.  The video (24 fps, 2 minutes) plays but after 10 seconds it is a few seconds behind the audio. The same video file in webm format runs perfectly. Just noticed the MP4 also runs slow in IE 11. Both formats run on time in Chrome 36 on PC and the MP4 is fine in Chrome and Safari on iPad. </p>