I have issues with a lot of the opening credit mashups on YouTube - you know, Veronica Mars with the Buffy theme, or Harry Potter with the Buffy theme, things like that. Usually they use the wrong font or style (hard to duplicate the way the words come on screen in the Buffy credits, 'cause that's a complicated effect), or choose the wrong characters, or something that just makes it a little 'off'.
But
this one (Veronica Mars cast and scenes, Angel style and music) is brilliantly done, and almost perfect. I'm quite impressed.
(And if I had any video editing skills at all, I would totally do a HP/Buffy one, because I do know the right font to use.)