Titaniumdoughnut is right - its all about essays, SATs, GPA, and your portfolio. That said, community service can only help. I did about 100 hours over 2 years (in part because I had to for the academic program I was in).
You might want to look in to doing something like tutoring younger students. I did that through my local library, 2 hours a week. Most the time I just sat there and did homework. It's good, easy, and even (gasp) educational and fulfilling.
Still, if you don't have a ton of hours, don't freak out. Just get some more, but not at the cost of dropping your GPA or putting off good creative activities (in general, community service has more to do with getting in to the actual university, and not the film school).