i dun think it's so much chopin as rachmaninov. it just sounds like, rachmaninov's style. ur sister's probably right. just to check, go and watch "the pianist" starring adrien brody. it's about the holocuast in warsaw, and brody plays a chopin concerto, and it sounds nothing like the piece in this movie. and also listen to rachmaninov's "rhapsody on a theme of paganini". u will find it sounds similar. hope i didn't come across as too much of a musical nerd here, but i hope it helps.

I'm wondering about that song too. My piano teacher said the style is similar to Chopin, but I have not verfied that myself. Hopefully I'll have time someday to listen to Chopin and Rachmaninov's work.