The SnitchSeeker has posted an interview with an extra from Harry Potter and the Prisoner of Azkaban in which she describes how she got a part in the movie, filming the scene when Seamus runs into the Great Hall with the Daily Prophet yelling about Sirius Black and mingling with the stars "...and of course whenever Tom's around there are giggling girls..."
SS: What were the sets like?
Christina: The attention to detail really is amazing. Every set I visited was fully dressed. Some of the best were the DADA classroom and Hagrid's Hut. Honeydukes was fantastic!
SS: What was the atmosphere like on set?
Christina: Strangely, I wasn't nervous at all. When we all sat down it was quite quiet, with everyone staring around. But after you'd sort of got over the fact that you're in THE Great Hall, you relax a bit and start chatting to the students sitting next to you and fiddling about with whatever's on your table and deciding what to do with it when the cameras started rolling. I had a book, a quill and a leather bag to play around with. And we also played some wizard version of Tiddlywinks which kept falling on the floor.
Read the rest of the interview here.