MicroHD (often abbreviated as m-HD), a reencoded high definition video file, typically targeted at reaching a good video quality while keeping the file size under 2.5 GB
Basically its usually very low bitrate 720p movies or whatnot. You can find quite a few on bithdtv, which is why the tracker has turned into a joke. HD + Low bitrate = Crap anyway you look at it.
http://bit-united.com is what your looking for. Not sure if you can sign up still. But they just opened their tracker, they were originally some rapidshare forum or something :ermm: