Jeff, if your concern is the large amount of storage required for the uploaded movies, you're likely on the right track with NAS if you're planning for more than just a few users, but there are many more ways to attach to it than just mapping a drive. Which of these is optimal will depend on many things, including the OS and hardware underneath your web server, NAS, and network, your own expertise and comfort level supporting a given option, and the requirements of the application(s) you will be developing.
The good news is, storage is cheap, gigabit ethernet is cheap, and things like iSCSI and ATA-over-Ethernet provide much cheaper alternatives (as opposed to Fibre Channel) where performance is important -- as I would imagine it would be for encoding and streaming video.
I also feel I need to advise you that if this is going to be a professional endeavor in any capacity (which is what S.F. is about, after all), you need to at least consult with someone who knows what they're doing with respect to storage. If you're going to hold a large amount of video (or any other kind of data) for people who expect it to remain available, you need to think about things like redundancy and backup, and to not confuse the two. You're essentially proposing to provide an alternative to YouTube for independent film makers -- not a small undertaking, and in fact even if it's NOT a professional endeavor for you, if others are going to depend on your efforts to store and disseminate their work, it's your responsibility to ensure these concerns are taken seriously. I don't mean to discourage you at all, rather to encourage you to involve others' expertise directly where it's necessary. Good luck!