I've been wanting to reply to these posts but didn't want to further derail the other topic so I'm glad it is here now.
I think that art can be anything. Even something like an AMV.
The reasons for this are exactly those that people have already stated in their arguments
against it being art.
For example, if art to you is supposed to be something that is "good" or "meaningful" then you can't possibly say that an AMV
isn't art.
Say for example i drew a picture of a cat, why? because i like cats, and for no other reason. However that picture would have meaning to me, because it is a part of who i am if you will, just like AMV's are created by those who are into anime... It is a part of their life through which they have decided to express some sort of creativity, be it from boredom or an actual motivation to create "Art"
Anyway, back to the cat drawing, to me it would be art, no matter how good it looked, it could be a few lines in a rough shape of a cat or it could be compared to the works of Michael angelo or Divinci, it doesn't matter, it's still art.
Take real life examples from the "Art world" aswell.
Let's pick on Tracy Emin, I used to think when i was in art college that none of her works could possibly be considered art, i mean all she's done is exhibited an un-made bed, and a bird on a pole!
But now i have the view that art should have meaning, and if that un-made bed had meaning to it, which it inevitably will, then i will consider it "Art", it doesn't matter if that meaning linked to her past or just her desire to make a bit of cash.
Just like i consider the keyboard i am typing with now as "Art", it has a meaning, it has reason.
I am having a difficult time trying to get my thoughts on this down since it's such a huge subject but hopefully you will get the idea of what i am trying to say.