People who don't use Flash can vote on stuff on NG, but you shouldn't just say "Oh, this isn't the greatest thing ever" and hit it with a 0.
An average NG user can come in and say "This isn't entertaining me, I'll give it a 1 or a 2", that's fine. If you've never used Flash, or haven't used it much at all, it's pretty hard for you to determine which movies involved no effort at all. Those are the only movies that deserve 0, ones which involved no effort at all. So unless it's blatantly obvious that the person spent like 15 minutes making it, then go ahead with your 0. Otherwise, maybe you should consider a 1 instead.
Oh yeah, one more thing, if you've never made a movie, don't write reviews as if you're some kind of expert on Flash just because you watch movies at NG.
Kthnx