How can I record live gameplay and play it back late from a diff. angle?

I’m making a game where there will be big and violent shootouts between different teams online. Now if I wanted to make a video about the shootout from a different angle? Like if I shot someone to death, and I wanted a close up on the gun when it shoots, how can I do that? YES, I know UE4 doesn’t support it. But how do I do it manualy? Tell me something like how to record the actions and put it into a 30 sec timeline.

See also https://answers.unrealengine.com/questions/65172/how-to-record-some-real-time-action-and-replay-it.html