That's how producing a big complex tv show like this live works. It's all planned out down to the minute.
How do you think the cameramen know where to go during the dances? Have you ever watched how many people there are on the dance floor before a dance starts? Look sometime when they show the floor in a long shot before the actual dance starts. There are multiple cameramen and at least one floor director. That's all planned and rehearsed too. It's really quite interesting to watch a big show with so many different parts being put together by production.