V5 rear outside camera

What is the red wire for on the V5 external rear camera. All I have found in Google was a bunch of people asking the same question but no answers. How is someone supposed to install it properly if Rexing doesn't provide installation instructions? I suspect that maybe it's to install to the +12V of your back-up bulbs to turn on when placing transmission in reverse but that's just a guess. Seems like that would be pointless though since the camera records whenever there is power unless the external camera is meant for other applications.