I just can't understand why software decoding of video would be that slow if you're implementing the stuff using standard api calls. VLC & MPlayer run great on

I just can't understand why software decoding of video would be that slow if you're implementing the stuff using standard api calls. VLC & MPlayer run great on the mac and I doubt they're using undocumented api calls to play video -- I just don't understand why flash video runs so slowly. I'm guessing they just have a really crappy video software architecture.