See Problems watching videos, see this (click on blue link). It has advice on how to get the best out of viewing videos on OSX. Having multiple players is wise for Mac. I recommend both VLC and MPlayer. Also getting Perian is wise for QT Player. Perian gives more video & audio playback formats than DivX codec plug-in or its player does.

Sometimes audio is encoded in a format some codecs cannot read well.

i got the VLC and it worked. i appreciate the help, thanks!