If you want to watch a good documentary, watch "Don't Fuck with Cats." It's about the hunt and capture of Luca Magnotta, who killed and tortured kittens and killed a student. There is some scenes where they sort of show clips from his videos of killing kittens, but they do not show the whole footage. So, be warned. Glad this guy is going to spend the rest of his life in prison.
Three episodes: About 1 hour each.