Who's rights anyways?
 

Okay here's one for ya. I want to use previously published music (e.g. Doors, Bob Marley, etc.) for a short film NOT DE BE DISTRIBUTED FOR PROFIT. Just to be a private Demo Reel. And maybe a film festival. Do I still need to worry about copyright infringement?

Don't know about the private demo, but any reputable festival will require the music to be cleared. Many publishers offer "festival rights" but for stuff like The Doors or Bob Marley - you're probably out of luck.

Okay, fair enough. But, what about for use on you tube or Vimeo just as a demo reel?

Nope. Whether it's for profit or not doesn't even enter the picture. No money needs to change hands for any reason. ANY copying and distribution of copyright works for ANY purpose whatsoever, except for the few exceptions defined in copyright law as constituting a 'fair use' defense against an infringment action, requires permission from the copyright holder (and nothing you're mentioned even comes remotely close to the legal definition of 'fair use'). Period, end of story. It doesn't matter why you're copying it or if money is the farthest thing from your mind. Whether you sell or give away the copies or just post them in public view, you must have formal permission from the copyright owner. As for a demo posted on YouTube or Vimeo, people have been sued by copyright owners for use in pieces that are even less commercial than a demo reel from someone looking for work. Remember the woman Prince sued for the video of her baby dancing in the kitchen to one of his songs? It wasn't even a demo reel from an aspiring filmmaker, it was just a home video that a proud mom shared because she thought it was cute. She still got slapped with a lawsuit for copyright infringment.