Good film but they were way too close. They should be a half mile away.
Acetylene makes sense but I would have thought that it burns with more smoke, like at the very last. I think it is a very good guess. Note that the cylinders were not secured.
I would love to see the accident report.
Nope this isn't the US, they aren't pansies. they only would have been too close if someone would have caught a cylinder in the face