I bought OEM equipment. My OEM one was threaded fittings.... this is identical...
I'm talking the trans line AT the radiator. But I might have fixed it. After trying 3 times in the Meijer lot I did a last ditch effort, and just drove off without checking if it leaked. When I got back to my apartment, there was no visible leakage. I started the car up... and.. no leakage. Hm.
SOLVED
But if it does leak again, I need a countermeasure. Probably a flare seat gasket.
Video update: