[alephnil]

> This property is more a function of the encoding parameters of the video stream

Not really. Formats like mp4 can't be parsed without reading the container header, that may be at the start or end of the file. Thus you can't read an mp4 by starting in the middle without reading the header and then seek to the middle of the file. This is the case regardless of encoding parameters. With mpeg-ts on the other hand, you can seek to a random place in the middle, and recover the stream on the next Iframe. Not many other file formats allow this.

[kuschku]

Of course you can start an mp4 at an arbitrary point, that's what fragmented mp4 is for :)

It's just lots of independent separate mp4 files concatenated into a single file.