Currently Being ModeratedJan 22, 2013 8:02 PM (in response to tronjer)
If that does not work, open the MP4 file in QuickTime Player and type the letter i while holding down the command key. Tell us the dimensions of the clip and everything you see next to the word FORMAT.
Currently Being ModeratedMar 9, 2013 3:36 PM (in response to gsquare43)
I don't have any personal experience with this codec, but I did find this discussion from 2010.
Currently Being ModeratedMar 10, 2013 1:51 AM (in response to gsquare43)
JVT/AVC Coding 720X478 (853X478)
ACC 48000 Hz, Stereo (L R)
The full name for JVT/AVC is Joint Video Team/Advanced Video Coding. It's a variety of H.264.
I've noticed that videos converted using Handbrake show this format. Possibly because Handbrake uses "H.264 (x264)" rather than the standard H.264 when converting files. So it could be associated with the x264 codec.
See here for more about x264:
JohnMacBook Pro (15-inch Late 2008), OS X Mountain Lion (10.8.2), Sony HDR-SR7 & DCR-TRV20E