icreatedthisjustnow

I'm a big fan of the pre-movie montages; I feel that I've lost if I don't arrive early enough to catch all of it. Questions:

1. Who is responsible for creating them? Is it a group process?
2. How long does it usually take?
3. How far ahead of the movie release do you start?
4. You always find super-obscure clips. What's your larger library beyond YouTube that you draw from?