add new head with OE video in expedition

trying to add aftermarket headunit to 2004 ford expedition w/ oe video. will get audio but video is lost when oe headunit is removed.

Found this, hope it helps:

Accessing Video Out From the 2005 Lincoln Navigator
Sean Young, co-owner of Sound Decision in Montgomery, Ill., sent in another video tip, this one on the ’05 Navigator (see November 2005 for this same application on the 2004 Suburban). He shows how to add audio and video RCA output leads to the factory overhead DVD player. The A/V signal can then be sent to any external monitor. In this install he outlined the wiring steps involved when the factory radio is replaced with an aftermarket monitor radio and video is sent to the new radio’s screen. After the factory overhead video console is removed, look for a gray plug entering the rear of the console. This is where your audio output wires can be found. There are also input wires that need to be reconnected after the factory radio is removed, otherwise the factory headphones will stop functioning. You must cut the input and output leads from the main harness as you will only work on the gray plug side. Individually tape off the wires going back through the vehicle, as they will not be used. While you are connecting the inputs to the outputs this is when you splice your audio RCA leads. At the gray plug going into rear of overhead console, connect the following:
Pin 7 – Left Input(+) – Red to Pin 5 – Left Output(+) – White
Pin 17 – Left Input(-) – White to Pin 15 – Left Output(-) – Green
Pin 8 – Right Input(+) – Orange to Pin 6 – Right Output(+) – Red
Pin 18 – Right Input(-) – Pink to Pin 16 – Right Output(-) – Black
The video output can be found going into the side of the overhead console. The video wires are twisted together. Yellow is the positive video signal and Black is the negative video signal. This is where you would connect your video RCA lead. The last connection involves a 16-pin plug that originally went into the factory radio. This plug will not be used when installing the aftermarket radio, but one wire does need attention. In this plug you will see Pin 6, GREEN/ Black. This wire must receive an accessory 12-volt positive in order for the factory overhead console to power on.