Update!
This plugin was originally meant for a game jam, and was very buggy and not particularly well tested.

Someone else used it for another gamejam, so I fixed it up a bit. It's still kind of buggy and weird, but it's better than it was.

Things I've added:
Play a common event before and after the rewinding.

Turn on "Turbo Mode" to make rewinding go forever, rather than just 5 seconds. You can press TAB again and again. Enabled with the script call:
Gimmer_Core.BKR.turboMode();

And a bunch of bug fixes.