Problem with playing videos

[Guest]

I have a Dell inspiron 6400 laptop with vista ultimate installed and when
ever I play a movie windows turns off the screen after 20 minutes (that's the
time I told windows to turn the screen off when idle). In the power
management I chose to prevent idle sleep while sharing media but windows
still turns off the screen. Is there any way to prevent this while I watch
videos?

 

[Guest]

Move the mouse every 19 minutes.

 

[Guest]

that seems a bit dumb, there must be a better way to handle this.