Here is the standard pin assignment for these types of Panasonic cameras. You can hook the grounds together.
You only need the first 4 pins and I am not even sure about pin #4. I just joined it to the other ground pin. I cut the leads for pins 5 & 6 off completely.
Pin #1 will be your 5v positive input. Wire this along with the red wire on the transmitter. Cut the plug off the transmitter unless you are lucky enough to have the matching plug laying around.
The two GND wires (pin #'s 2 & 4) should be wired to the black wire on the tx.
The video out (Pin #3) goes to the yellow wire on the tx.
The battery power should go to pin#1 and the red tx wire.
The negative power lead goes to both GND wires on the camera and the black wire on the tx.