PlayClaw is the most powerful game video recorder in the Universe! Try our game recording and streaming software for free!
The CCCP: Combined Community Codec Pack is a codec pack specifically built for playing videos (including mkv).
Freeware Video CODECs
CodecVisa: Powerful video codec analyzer.
3ivx develops audio/video codecs, and streaming/transcoding components for H.264, MPEG-4, HE-AAC and HLS on Windows, Mac OS X, iOS, Android and Unix/Linux.
This blog explain about various video codecs with their pros & cons
Data compression & lossless video codecs.