MP4 is high quality 720p made for streaming to most all hardware, such as your Xbox and PS3.
MKV is slightly higher in quality than MP4, and is also in 720p, mostly unsupported by everything except your PC.
AVI is 396p, standard(lower) quality, supported by your dumb DivX Players.

Keep in mind that before you complain, Taka does not handle the encoding of this series, so don't bother complaining to us about it please. Thanks.
Also, yes... we will be releasing episodes two through five. Two is currently in the works now. Expect it soon.