2 Questions. I'm converting some mkv files to m4v to play on my apple tv 3 but i'm not sure on the following: 1. Should I automatically change the profile to main @ 3.1 since it's playing on an apple tv 3? It loaded up as high @ 4.1 2. How do I optimize the file? Do I first convert the file to m4v and then optimize? What exactly does that do?