Preserve the movie's aspect ratio

- Not a complete solution (if you manually set the aspect ratio
  the layer won't notice it) but it's a start.
Fix QT movies hanging after unfullscreening

- Fixes the bug where after unfullscreening a QT movie
  would freeze it.
- There doesn't appear to be any real reason to orderout
  the window as it's going to be released shortly anyway.
  If we need it to happen we can do it after we've moved
  the movie view.
Remove some unnecessary window flush commands

- I don't see why we would need these, especially now that
  the movie view is CoreAnimateion-based. I also don't see
  any detrimental effects from removing these commands.
  If strange visual bugs start showing up with fullscreen
  transitions then we'll know where to check first.