I can't remember who posted this on Twitter yesterday, but it is indeed a dramatic reading.
I'm a little mystified at the fanfic thing, even though I'm probably guilty of it myself to an extent. I've never had the urge to write myself into someone else's book, but I've written a few stories for my MMORPG characters, and that's technically writing in someone else's setting. It was fun, and I enjoyed creating a story with other players. But Harry Potter fanfic? I'd rather create my own world and run amok in it.