>.MKV container

since when did you think encoders were out just to please you?
since when did you all think encoders only make these files just so the work on
your dvd players and ps3's?
does that answer your question?

Oziman is right shorthair8275....if you want to know why other uploaders/Encoders uses .mkv...read this...matroska

Try this also if it helps...

Why others use MKV format

#1 – It’s Open Source

open_source_iconQuite frankly being open source is one of the best steps a media format can take towards acceptance. This means that anyone who wishes can add the format to their product without paying outrageous licensing fees. The end result is that the format is widely usable in most media player software and the tools for creating MKVs are extremely well polished to boot.

#2 – Awesome Free Tools

Number two goes hand in hand with number one. The free source community has some of the best programmers there are. It attracts these people as a sense of community and philanthropic duty. They also aren’t afraid to ask for help from the community and they often get it. That’s just the nature of open-source. The end result is some of the most usable, highly developed tools for utilizing a format ever created.

#3 – What It Can Hold

AV-256x256 Matroska is a container format, which means that it only holds the content. What makes MKV special as a container is what it can hold. Matroska has the flexibility to contain almost any audio/video format, including most lossless types, making it perfect for high definition content. What sets it even farther above other formats such as MP4 though is it’s ability to also pack in multiple subtitle languages, track information, multiple audio streams and more. Everything in one file!