>>>When you say only use one programme at a time do you mean if I streaming a film only to open one window?
I simply mean that it might be unwise to try to play one video file (whether saved on your hard drive or streamed from the web) in one player while simultaneously trying to play a different video file, in a second window, with a different video player. It's possible that they might send conflicting commands to your video card (although it's equally possible that it would actually work). U
Unless you're in the habit of (for example) watching Match of the Day with your left eye while simultaneously viewing Casualty with your right eye, the situation is extremely unlikely to arise anyway ;-)