What is this video format, and how do I convert It

"Matroska is just a ""container"" format. You can use any sort of video and audio compression for the streams stored in it.

You can convert Matroska files with VLC (http://www.videolandotorg), ffmpeg (http://www.ffmpegdotorg), and mencoder (http://www.mplayerhq.hu)"

"this will do:

SUPER © Simplified Universal Player Encoder & Renderer.

A GUI to FFmpeg, MEncoder, MPlayer,
x264, musepack, monkey's audio, true
audio, wavpack, ffmpeg2theora and the
theora/vorbis RealProducer plugIn.

SUPER © will convert any VOB, ASF, AVI, MPG, RM, OGG, MKV, MOV, MP4, WMV etc.. with a single click.

SUPER is freeware."