Is there any way to stop .mpg from opening up in the QuickTime plug-in in my browser (whether it be Firefox or Safari) and open them up in QuickTime or VLC Player...
Externally from the page? Not that I'm aware of. Even if you install the VLC web plug-in, I think it plays in-window (not being a VLC user, I could be blowing smoke, so someone correct me if I'm wrong).