If VFords is still around, here's one. It sounds like the 2010 Edge's have a unit that is equiped with the capability to have a rear view camera but Ford doesn't offer that option on the Edge for some reason, apparently though they do offer an aftermarket solution for $800 or something. Supposedly the unit though has an input on the back that would accept a camera, however you need a specific cable to connect to the Pins on the back. Any idea what the part number is?
See here for more info ...
http://www.fordedgeforum.com/index.php?showtopic=3850