Can I stop OS X Lion from dimming the screen when using Skype, YouTube etc?

Question

I just got my first Mac and some things are not very obvious to me.

Is there a way to stop it dimming the screen while on battery power when I'm on a Skype call or watching things on YouTube?

I don't want to completely turn off this behavior; I'm just curious if OS X can detect if my computer is in use beyond keyboard and mouse input.

Answer 1

Generally deactivating dimming

Do you generally want to disable this option? Under System Preferences » Energy Saving, you can disable the auto-dim for battery. Might look different in Lion.

In YouTube, watching videos on full-screen will not trigger the display sleep. I can imagine the same goes for full-screen Skype.

Temporarily deactivating dimming

If you only want to deactivate it temporarily, you can do so by using the Hot Corners feature.

• OS X 10.6: System Preferences » Exposé and Spaces » Exposé » Active Screen Corners
• OS X 10.7: System Preferences » Mission Control » Hot Corners

The trick now is to have a hot corner for deactivating the screen saver – yes, even if it's not running at the moment. Now, when you are using Skype or watching YouTube, just move your cursor in this hot corner. It will prevent the display from sleeping. When you're done watching or using Skype, move the cursor out of the corner again.

Answer 2

This has (most likely) nothing to do with YouTube or Skype; your Mac dims the display because you're not using the mouse or keyboard and you're on battery power.

You can deactivate this behavior by opening "System Preferences", selecting "Energy Saver" and unchecking "Automatically reduce brightness before display goes to sleep"