Perian just ended development and the code is moving to Google Code or Github.Did you try installing perian?
And what is it you don't understand about VLC? Install the application (which I believe is drag and drop). Then right click the file you want to play, choose "open with" and then choose VLC. If it doesn't show that options, choose "Other..." and the find VLC.
VLC should open and play. Else hit the space bar.