You may need one like this so you can separate the inner & outer conductors. Just keep them as short as possible so the shielding is still effective.
I used another relay (also switched by reverse lights) to put an earth on terminal C1 in the tuner. It doesn't matter what is displayed on the screen, it will force it over to display the reverse camera & then switch back again when finished. (I suppose if you could find a triple throw relay you could do everything with the one device.)
To bypass the in-motion cut out, I extended another wire from C1 to earth via a switch at the front. When operated (& not in reverse) you use your remote to watch TV or switch to DVD, playstation or whatever is on your aux input.
The Xanavi guys say that it can be done in the programming. So if you haven't done the English conversion (& were intending to have it done), you could ask them about it
I don't have any leads made up, but can make one if you want. They're pretty straight forward if you have an old computer lying around.
Cheers, Leon.