Broadway Bat Mitzvah Entertainment

We are also planning a Bat Mitzvah based on musical theater...both Broadway and movie musicals. Any ideas to incorporate the entertainment into it? We have a screen and projector available and were thinking of showing scenes from some movie musicals. We have a DJ/MC who is open to pretty much anything, but we are not sure how to involve the guests. It might get old watching scenes from movie musicals without anything interactive. Those of you who did this type of theme, did your entertainers do something interesting with it, or just the usual DJ stuff?