But requiring mp4 as container is a bad idea in my opinion. To playback an mp4 file you need to have it wholly (please correct me if I am wrong) so you cannot start watching before you downloaded it all. MKV would be so much better.
Please do not blindly reply with "But my XYZ device does not support MKV". Scene rules/standards have a lot of impact and might help making vendors support Matroska.
You are. By default, many tools put the meta data of mp4 files at the end of the file which means you have to have the whole file before playing. However, such mp4 files can be "fixed" using tools like this:
720p or better videos on youtube are all MP4 now. You just have to move some atoms around within the video file to prepare them for "streaming" playback. There's open source software to do this.
Then again, the ability to play an incomplete file is not really useful if you're fetching a movie via torrent, which is what I would assume most of these guys are using.
I suspect scene standardization on MKV would probably encourage Apple and Sony to deliberately not support MKV (instead of not supporting it out of laziness, as they currently are).
Other then that, only a few embedded products support mkv (TVs, set top boxes). These are pretty much impossible to update, so it is pretty much impossible to recommend matroska at this point, since a large amount of people would watch these videos on such products.
No more transcoding from xvid/divx.