1) One-minute sketches and full-motion video can be very pretty. It's almost completely unrelated to what we need. Try sending samples of things we actually do.
2) Making things move very slowly is either suspenseful or boring. If you're not certain it's suspenseful, it's boring. It's probably boring anyway, though.
3) Demo reels should be both longer than fifteen seconds and shorter than fifteen minutes.
So far, I'm not sure I've seen one person who's actually followed even two of these guidelines, let alone all three of them . . .