From listening to Car Talk, I've learned that most single exhaust vehicles locate the exhaust on the opposite side of the fuel fill. Therefore, since the explosion blows off the rear left fender, it appears that he wasn't paying attention, the tank overflowed, and gas made it's way to a hot exhaust pipe?
Yeah, but liquid gas pouring out in open air wouldn't explode, it would just make a big fireball. That looked like a trapped vapor kind of explosion. Unless I'm just wrong, but I don't think I am. I've been stupid and used gas and deisel fuel enough times to fuel fires in land clearing operations to know how it burns. Looks like a spark from when he touched the car body, maybe vapor in the top of the tank being pushed out of the filler, and the spark somehow ignited the vapor. But then the tank would have to have had an oxygen source. Maybe a broken line in the tank filler letting vapor get into the empty space around the tank, and in the cab? I'm curious as well, never seen an explosion quite like that. At least not from a car.
It was a guy in Iran filling up a propane tank at a compressed natural gas filling station. Some people retrofit their cars for cng and cheap out on the tank by using a grill tank instead of a certified cng tank. Problem is cng tanks operate at a lot higher psi. Grill tanks work as long as you don't let the filler keep going into the higher psi. He forgot then, realized right as it was too late.