It is not a straight forward thing to use multiple cores. There are some things that can run in parallel and some not. The primary game typically runs on one core in all games. Then things like filling sound buffers, loading textures filling buffers from communications run on the others. The multiple cores does not really make a game run faster, but what it does do is prevents the small stutters.
The film viewer loads textures on the primary thread so that there is not a period of time where the objects are white, like when you enter the main game, or alt tab. If it didn't do it this way some when making videos from the films, they look correct.
HiTech