Hi,
I actually have a couple of these (not same brand) that I've put together for looking at security cameras as I set them up. They come in real handy for seeing what the camera is looking at at the same time your adjusting it. I also rigged one to an old helmet that goes to the reciever from video off an R/C car. Sort of a poor mans heads up display.
My experiance on these is just this -
I look for the shielded set of wires which usually equate to "video in". Then I try to establish ground by looking at the PC board, or merely "Ohming" it out. Then to find V+, I merely go through each of the remaining wires while I've got ground (V-) hooked up, when I see it light up, then I know I've got the correct one.
Here's a couple of things that you might find -
Occasionaly you'll find one that has an LED in there that was designed to light up in the record mode. Occasionally you'll find other LEDs as well, and once I found one that had an additional input that provided some "burned in" on screen graphics. Odds are, that depending upon how old this unit is, you probably have some LEDs in there that would account for the additional wires.
Hope this helps!
Kel