Perfect thank youthat wasn't in the video.. ultimately when you take the two side panels off and pull back the rear wheel arch carpet, you will see this Black/White plug tucked down in the harness. Tap the red/Gray wire and then use the bolt on the chassis (Below that plug, pictured below) for the ground. When you are all done, use some zip tied to tidy things up back there.
I see your fan of the POSI-TAP, love those things!