Okay, final answer.
This is straight from the horse's mouth. Not to say Robert Orf @ TIFFEN is a horse, ya unnerstand,.... but you know what I'm sayng.
He confirms that you have two options for 12V power appropriate for running that light.
1) The small (Size 0) 2-pin: 1=+, 2=G
2) The larger (Size 1) 4-pin under the cap at the bottom: 1=Vid shield, 2=Vid signal, 3=+12VDCD, 4=DCGrnd
Both ports take current direct from the battery. As such, a 50W, 4amp draw is gonna drain 'em pretty quick.
Slight correctiuon: The MOGAMI quad I usually use is 26AWG, 24AWG for the mic cable.