One of the cart wheels appears to be dragging. If Tom Hanks' character in Apollo 13 was describing the cart's movement, he'd probably use the term, "wicked shimmy".
Is that 2 welders. I know little about them. We had an arc welder. When it died, we got a welder that feeds wire. I've seen the welders that take 2 tanks used, but never used them, myself.