Screen/DVD player Issue, Please Help

I apologize if this has been covered elsewhere

So heres the problem:

On my macbook when my power cord is plugged, and I am watching a DVD on the "DVD Player" program, my screen will darken after a few minutes, and eventually the screen will go to sleep. However, when my computers power cord is unplugged, this does not happen, the screen will stay active for as long as I am watching a movie...

Very annoying, any thoughts?

Thanks!

Welcome to Mac forums.
Go to >system preferences>energy saver>power adapter, and change your display settings.

Thanks for the welcome!

Thanks for the advice, I already checked that out... It didn't have anything particularly pertaining to DVD watching...

It would seem to me (perhaps in stupidity) that while my screen never darkens while watching DVD's while the power adapter is UNplugged, why would it darken while plugged in?

Also, my old Macbook's screen did not darken while watching movies with the power adapter plugged in...

Not that I don't appreciate the help! Thanks!

So this is only happening while watching DVDs, but not when your computer is idle?

Well, when my computer is is idle the screen will go to sleep, but my feeling is that it shouldn't go to sleep ever if I am watching a DVD. At this point it will not go to sleep when watching a DVD unplugged, so why should it go to sleep while watching a DVD plugged in to the power adapter

Your correct, it shouldn't be sleeping either way if you are watching a DVD.
I can't think of what may be causing this, but I would give resetting the SMC a go.
Intel-based Macs: Resetting the System Management Controller (SMC).
If that fails, I would try setting up a new user account, and seeing if this happens with that account.