/lurk mode off....
To play any .mkv file or any other file format you need only one player and that is the "VLC Media Player".
VLC is a free cross-platform media player.
* It supports a large number of multimedia formats, without the need for additional codecs
* It is available for almost every OS
* It needs little CPU power
You can use this player to view virtually any video format on the web and DVDs too.
.MKV and .OGG file formats allow you to view multiple subtitles and audios.
Such as being able to switch between english and japanese.
I've included a link to the player here...
http://www.videolan.org/
Check out the site you'll be surprised at all the formats this player can use.
Features list..
http://www.videolan.org/vlc/features.html
Hope this helps.
/Lurk mode on