Here are some more examples of (I hope) correct usage.
I think I got these explanations correct, other than the fact that I made heavy use of run-on sentences to describe those situations indicated by each usage example. Feel free to make corrections if you find any, though.
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- "The performance started with dancing and finished
I agree with Philip's answer ! If you just watching the performance, you may use 'a dance'. But if you join the performance, you'd better use 'dancing'. (Desimaliati)