This is just my take, I think it's mainly due to ethical reasons and the fact that AMVs are their real concern or value, so things we value like video quality and sync they don't care about. Of course, this is purely my opinion and based on my own experiences with them. In order to have several people I know be able to see my work I did upload two things there, but was so dissapointed with their quality and the fact that it threw off so many of the syncs I'd worked hours on that I haven't done anything since.Why do we hate this site agian?
I think YouTube is designed with a different purpose than our site, but when so many amateur makers disgregard us and turn to them it's a bit of a slap in the face, since we've worked hard to build this site over the years but then a sort of young upstart shows up and becomes a threat, while offering lower quality and a looser moral code than us, and just in general less professionalism (based on the experiences I've had again, after this site I was somewhat dissapointed by the feedback I was getting and having my videos shamelessly stolen with no consequence was annoying, to put it lightly, hence I've stopped using it and am considering terminating my account)
I think YouTube has the right to have some of their stuff up, but when they start going onto our turf there's bound to be bad blood between the two sites. But that's just my interpretation of it.