Two strikes against QT;
1. QT videos will play only in a QT player which the target must install from the Apple website…it is not easy.
2. QT video must be encoded with Soreneson’s professional codec to have near comparable efficiency with Windows Media Video. This codec costs about $300 or comes with Squeeze ($350).
If your target is media or creative folks then QT is fine, but most other folks dont have the QT player.