friend of mine bought a 2011 f150 without backup camera but the seller also had a tailgate from another year with the camera and so swapped the tailgate. Not sure the year of the tailgate but I figured out the wiring from the plug in the tailgate which is different from the ones posted here and so maybe this will help somebody.

Power + to purple/brown
Power - to black/green
Video + to white/green
Video - to brown/purple