I have the same set of unused audio and video RCA cables attached at the front TV in my 31FS. The set that is connected to the TV allow sound to go TO the head unit in the dash and be blasted throughout the cabin on that system. Changing the TV speaker setting changes where the signal goes.... It is my understanding that the second set of wires is for a DVD player or satellite system. This will allow whole house broadcast through the head unit to al the RV outlets...Rear TV, outside TV etc.
It would be nice if the manual covered this.