For about a year, I was super frustrated with my MBP because I would watch movies or shows, or listen to music, and the thing would fall asleep. That is until someone told me about Caffeine:
Caffeine is a tiny program that puts an icon in the right side of your menu bar. Click it to prevent your Mac from automatically going to sleep, dimming the screen or starting screen savers. Click it again to go back. Hold down the Command key while clicking to show the menu.
I love this program, and would almost say that (with the exeption of Photoshop), this is my favorite program running on my mac.
And by the way, if you’re trying to fix the horrible volume issues with your MBP, click here.