Diesel Bombers - Truck Won't start need help please (Video)

I'm completely at a loss right now about what's wrong with my truck. I'll keep this as directly to the point as possible. It hard starts but it never took more than 5 seconds to fire up but I determined it to be air getting in my fuel lines somewhere and and it seemed to be the return line banjo fitting on the back of the Cylinder head. I tried tightening it down but after doing that it leaked from the top of my tank so I tightened down the collar around the whole sending unit as much as possible. Now today it doesn't wanna start so instead of trying to explain it I took a video. I'll admit it that I'm kind of panicking and it could be something as simple as the batteries but I can't help but think its something that I have done. Here's the video sorry for it being vertical.