The software has the capability to *convert* mpeg4 (some) mp4, mov, and I think like two others.
When they say "supports" this really means converts.
The best format is .wmv, and quite honestly, there is better software available for converting videos from mov/avi/mpeg to wmv.
Works the same way with music. Although it supports mp3 and wma, it only "supports" wma lossless by converting it. :-/