All ur motion is ourz

[hounddoghowlie]

I have noticed that I can sit and watch a 1.5 hour video with nothing happening to my computer.  However, if I get up and go work while listening to a video in the background, when I come back 30 minutes later, the screen will be black.
How does it know when I'm not at my computer? 


This is a question I've been asking myself, because this computer is custom built by a man I do business with, and my monitor doesn't have a camera. 
I guess I found my answer; it's in the browser.

 could be your display setting. check your display power settings, they might be set to power the screen off after 30mins.while watch the video you may be moving the cursor, volume hitting a key or some activity that keeps it on.