Video. Laptop---->Television via S-Video

Hi,
I have done something which stops my laptop feeding whatever is playing in the active window to a television via the s-video out. I used to play video with VLC or DivX player in asmall window on my desktop and it would then be able to be seen full screen on a television.

When I go into display properties, the second display is not active, but if I select extend my Windows desktop onto this display it becomes active and I can then (by mouse) move the player over off the laptop screen and it appears on the television and can be played.

My question is, what have I changed to need to do this, where previously the second display was active and would simply pump out the video to the television without having to extend the desktop.

I have no idea what I've done.

Thanks for your time.