About people dancing in movies and tv?

Yes, they play the music while the shooting is taking place so that the dancers can be in sync. However the music being played live while they're dancing is not the recording used in the final film. The acoustics would not allow it. Music is added as part of the post-production. Most dialog on set has to be re-processed to filter out all the background production noise, or sometimes re-recorded in a controlled sound studio to get clarity.

Hope that helps!

There are a few ways to do this. In a film I did where there was a big dance number, they played a recorded track while the people were dancing. I was upstairs working with the extras, so was not involved in the filming of that scene, so can't say for sure, but what my knowledge would dictate is that though the music was played, it was shot MOS (it's a weird old-school acronym that basically just means sound was NOT rolling). They would most likely shoot anything with dialogue without the music playing. These are then interlaid in post. Music is added in post in EVERY situation I know of, as is a lot of the other sound. So the short answer is, yes there is music playing, but no it's not recorded. Other sound elements are added in post.

I would think there would have to be music or the entire dance crowd would

be moving at different tempos. I don't really know just how they do it though.

It could be that the music is live as it's being filmed or that the music is

dubbed in later from the same recording played during filming.