> To playback an mp4 file you need to have it wholly (please correct me if I am wrong)

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:

https://github.com/danielgtaylor/qtfaststart

> To playback an mp4 file you need to have it wholly

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.

Actually the latest utorrent lets you stream the video files while you're downloading them.

That's pretty cool. How does it achieve that? I'm assuming it assigns a higher priority to the chunks closer to the playback cursor.

By the look of it, yes. With well seeded torrents it actually works very nicely.

Bitcomet has actually beein doing this for ages.

If the MP4 is "fast start" the index is at the beginning so you can "stream" it.

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).

When DivX made their H264 codec, DivX 7, they actually chose the matroska container. Of course, DivX has lost a lot of the brand name recognition they once had (their logo used to be on nearly every DVD player), so the penetration of matroska in this respect isn't that high. There is also WebM, of which the container uses part of matroska, which might help penetration (of course, its people like Apple and Sony who aren't likely to implement WebM).

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.

I'm pretty sure it's already deliberate.

One upside of using mp4 is that most smartphone devices and tablets support it.

No more transcoding from xvid/divx.

You don't need the whole file. That would just be silly and it's used for streaming all the time. Also even though I would prefer to see an open standard succeed, the mp4 container does have a lot more support while mkv doesn't have any advantages for this type of use.