WARNING: This page is about a different car, the 2010 Saturn Outlook, 2010 GMC Acadia, 2010 Chevrolet Traverse, and 2010 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Video System Schematic - U42
Courtesy of GENERAL MOTORS CORP.
Fig 2: Headrest DVD Circuit Schematic (SPO Accessory)