If you really want to find it yourself, and you don't have an oscilloscope handy, the same thing could be achieved by running a cable to the video-in of a VCR with a monitor/tv plugged in. If you ground the ring of the cable to some metal part of the PXL and probe with the tip, you'll get an image from the PXL on yr tv when you make contact with the signal source (of course the PXL must be powered & in record or pause mode.)
Take one of the 4" lengths of shielded copper wire and prep it by melting a little bit of solder on the end. Carefully solder the wire to the spot as indicated in the picture. It is the second solder point inwards diagonally from the crook in the board where the metal plate has been pulled away. (please see the picture!)
Push the metal cover back down and resolder it to the four points. Then solder the other 4" wire somewhere on the metal case to provide a ground.