A wonderful opportunity for young actors! Well-rehearsed and they obviously are having fun.
Two comments: While pre-made "screen-scenes" are much less labor-intensive, children who wish a back-stage experience are missing a key piece of theatre. Also, while a 'mega' cast gives lots of kids an opportunity to be on stage, it makes it hard for the audience to see all the kids who are on stage at the same time. Both are just choices you make, of course.