I would like to send the video signal to 4 external monitors but only have one video out on the headunit. Does anyone recommend a soultion such a video distribution piece that will work on 12 volts?

http://www.epinions.com/auto-Mobile_AV_ ... tputs_KVDA

This will support up to 7 video outputs. Of course its Jensen so it might not be the very best of quality... But at least it somewhere to start.

I have a Pioneer AVH-P4900DVD with a Planet Audio video amplifier in my Chrysler that has four headrest monitors. Works really well and I think I got if for $20 or so.