Sure, Basic QuickTime player only comes with simple codecs/plug-ins. So you need to chase down others yourself such as DivX, XviD, 3ivx. We normally recommend VLC player because it comes with built-in codecs ... all you need:
VLC - (click on link) _ (choose nearest mirror site)
OH ... as far as .mov format goes, even though it started as a QuickTime format, apparently some Windows programs have started using a variation of the format but they often don't play with QT player. Very annoying I know. Most .mov files you find on Gnutella network are spammed porn.
See
Movie download issues (click on blue link)