Most wont be interested in this though figured id share it anyway - Use of reverse camera on demand.
So reasonably simple enough though a minor item to get it right. The reverse camera is switched by an active wire switched presumably from gearbox input and via ECU. Looking at the AV input you simply need to switch an active on the same input feed which works.
Doing so does back feed the circuit and power the beep & reverse lights which personally I didn't desire, especially if say driving down the freeway etc and people see the revers lights come on. So an easy fix, cut the input feed, solder in a diode to prevent the back feed of power and connect the new active switch wire upstream of diode.
Flick a switch on demand at any speed and dash shows reverse camera image, no beep or reverse lights.