The user is able to enter the rewind mode from the live game play using one or more controller inputs to view recent game play (e.g. rewinding, fast-forwarding, playing, etc.) and returning to live game play afterwards.

(Emphasis mine)

This doesn't sound like it's actually rewinding gameplay (as in like, Prince of Persia Sands of TIme style rewinding), which is what they seem to be trying to imply, but rather it sounds like it will just let you watch a replay of your gameplay to review it and see what you did wrong, which you can already do. I think all modern consoles (and Steam, etc.) have a 'Save last 30 seconds of gameplay' style feature. This is just adding a button to the controller to view that recording, from the sound of it.