To my understanding, there is the container format (MP4, MOV, 3GP, AVI) and the codecs (Theora, VP8, H264, XVid, DivX).
For what I understand, the container format and the codecs are independent and it seems that it would theoretically be possible to have a MP4 which contains some video encoded with DivX.
Would it work? I mean, would standard video players be able to play it?
Also, I don't understand why H.264 (a codec) is defined in the MPEG-4 (a container) specification.
As H.265/HVEC is to replace H.264, will there be a new container format? Or will there be some MP4 files containing some videos encoded in H.265?