Ha! someone pointed it out!
I realize that's a pretty big flaw in the idea, but at the same time I think it's possible to create a comment/karma system that helps both the creator and viewer. Yes, it would involve upvotes for videos/comments, but if someone leaves a comment on a video, and people agree with the comment, that person's comment all of the sudden becomes worth more; which helps viewers find videos that are worth watching. And the more people leave comments, the more people actually discuss a video, so the more everyone gets to the actual truth about said video; which helps the editor. The only thing I'm not sure about is making the upvotes publicly known.
But as a viewer, I would rather have suggestions offered to me than a rating lists to browse through. Because if I have a rating list --and a lot of the ones at the top suck-- it deters me from watching the rest. If I simply have suggestions offered to me without ratings, I end up spending more time actually watching videos, and coming up with my own judgement, instead of deciding which video I should watch next, and being swayed by the popular vote (in the positive or negative direction

)... which leads to being jaded, and never taking a chance to watch another AMV again. And if I still can't find anything I like, it's time to take the next steps: leaving a comment, or making my own videos. That way, I still have power in the system; instead of letting the system tell me what I like/should like.
So, comments and anonymous karma (upvotes) seem like the way to go IMO.
But hey... isn't that similar to a certain popular website? I can't quite put my finger on it...
Naww... it's not like
they would have put any thought into
their rating system...
(sorry, I don't mean to be sarcastic, but I don't think anyone should feel bad about copying a good system; although implementing said system is another issue.)
So, back to your original question Bashar: I agree that we need a system for finding good video; but I don't think we need to rely on numeric ratings.