Ok...so i've tried to watch mpg's and avi's on (mac osx) quicktime 6 but an error states "Software component needed by movie could not be found". What component is that? and where can i get it?

Next, i downloaded VLC and now an error states:

deinterlace: no valid deinterlace mode provided using "discard"

what the heck is that all about? i either get a still image or 5 secs of video then an error occurs. Please help me! How can I watch movies?