And who knows what path that will lead them down mentally in the future?

To play devil's advocate for a moment: If you're already an outcast without guidance a few horrifying videos aren't the problem. Video games, movies, and snuff films will not be the tipping point. Even if you could shelter such an individual from all of those things in the world, doing so would be an act of guidance. Something this theoretical person is without.

Edit: I'd also like to add that video games don't cause violence. :)