Well I'm looking for someone who can make up the PCB (The layouts are on there, just need to be printed out), then i'd love to have a go.... Anyone got a spare CID so I don't trash mine??? LOL I thought not!
That PCB looks to have been created on a milling machine......
....ow, did I mention we have a PCB milling machine at work 
If this ever comes of anything please consider me a potential customer. I'd like to rig it up with screens in the headrests and they would need to work whilst moving and the CID would need to work on SATNAV whilst that was happening. Only when I wanted to manually "flick a switch" would I want to feed the DVD output to the CID.
I don't want much eh?

(Moon on a stick, in case you were wondering)
Believe that the screen only shifts to alternate source when it detects an input (part of the logic on that interface built onto the PCB has).
On the video link on that site you can see that all of the head unit menu's and the clock / source bar at the bottom disappear when the video source is turned on so the interface obviously drives the lcd panel directly.
That'd be OK though, I would expect a manual override switch, so that I could simply just break the signal, via the switch, whilst I was in motion, or didn't want to see the DVD/TV output, and if I wanted to watch the TV/DVD then I could flip the switch and expect to see that instead of the SATNAV.
Or have I missed your point here?