I *think* that might be the shadow cast from the three "top" plates that sit on the rear assembly of the flame thrower...I am checking reference pics as we speak.
The rear of the flame thrower (near your elbow when you are wearing it) consists of a base block and three top blocks...on each side of each top block is a small half round ridge...that I think is what you are seeing. Here is a rear view...while I continue looking for he answer.
After reviewing various photos, I don't think it's a molex connector, but I do believe it's somewhat similar and plastic. If you look at various photos of the cubes mounted to that piece, you'll notice they shift and become misaligned. That's just my personal thought on it, though.