I've got over 400 videos spread out on three sites. I use highsecurityhosting.com for hosting, have a dedicated server with a dual core processor and 2 gigs RAM, a 120 gig hard drive that's half filled from the videos. I wouldn't want to go any lower than this config for any kind of serious use.

In June I used about 300 gigs of bandwidth. For July I've used 200 so far, about on par with June... and that's only from about three hundred daily visitors.