Hi, I want to buy the rear RC100F FULL HD 1080 camera and switch it from the 720p. I have the 650S-2CH -- will the Full HD 1080 camera work and compatible? Blackvue says the coaxial cable is the same but it will not record - is this true, if so why not? I want full HD in the back -- just got the 650S and dont want to spend another $400-$500 AGAIN on new model. Does anybody know?