This is a deleted scene from the movie of the Half-Blood Prince. I only read the book once, and I don't remember where it fits in the story-- maybe it's about Dumbledore's funeral.
And I haven't liked the HP movies I've seen all that much-- they don't look right. Perhaps I'd be happier with an animated version (drawn, goddamit, not CGI!) based on the illustrations used as chapter headings. The only thing I've been really delighted by is the initial musical theme from the first movie. It isn't Harry Potter, but it's a fine evocation of magic.
However, I love this video, and I like to think I'd love it even if I'd never heard of Harry Potter.
It back up my notion that, much as I can enjoy flashy special effects, fantasy movies still run on acting.
Link thanks to rm.
Addendum:: The embedded video doesn't seem to work--