Question for Mac users
 

.WMV files work fine for me but when I click on .mpg or .avi, the quicktime screen opens and I just get a question mark over the Q. Anyone gotten this before?

... I've never seen that - just a blank screen in the player maybe.
You should maybe consider getting the VLC player which plays pretty much anything you throw at it.
Also, make sure you have the divx codecs.

Re: Question for Mac users
 

same thing happens for me when i click any .mpg file. I have to save the file to my desktop and play it through Quicktime Player. I don't know why it does that. I'll post it here if I find the solution.

how do you save it to the desktop? I'm trying that method too

If you are using OS X and have a two button mouse, simply right mouse click and choose Download linked file. If you have the single button mouse, hold the option key down and click the file name.