The trouble with vids on Youtube is that, as well as the quality issues, they have this tendency to vanish. But I had to rec this one, because it's simply stunning:

I'm Still Here, vidded by RennyTheThunder - Zuko vid, clips from the whole series (although it's cut so quick that I'm not entirely sure if you'd be that spoiled if you haven't seen all of the show). I don't normally go for vids with a lot of editing/effects, but this one uses them beautifully; I'm just incredibly impressed by the way the cuts and f/x and song lyrics are fit together -- and on top of everything, it's a perfect Zuko song, and not one that's overplayed. This one's a keeper, and I wish the vidder had a website somewhere (at least I can't find one) because I really want a better-quality version of this!