A snuff movie is one featuring a person's death/murder for someone else's sexual gratification; I think it featured on an episode of CSI, once, and also the main theme of that movie "8mm" with Nicholas Cage in it (which freaked me out BIG time). I think it's an urban myth, but plenty of people reckon they exist.
@ the artice: *giggles stupidly* What a load of absolute tripe.
They'll be telling us sex is bad for us too, next. Reminds me of people that sell "DNA activation kits" to activate "100% of your DNA!" (without considering that that theoretically means your eyeballs will turn into fingernails etc).
Add technobabble, make your nonscience believable!