DVD Control Module
WARNING: This page is about a different car, the 2013 GMC Acadia, 2013 Chevrolet Traverse, and 2013 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
The two video screens are linked together by the DVD Control Module. This module allows screen 1 to source the media being played on screen 2. Video, audio, power, and remote signals are sent from the DVD Control Module, to each of the video screens. Video and audio signals are sent from the screen to the control module, and then to both screens.