Because it was funny to them.
Typical military FUBARs happen. There’s not much they can do about it at the time it happened, no?
Whoever packed those pallets needs to worry, but not those watching.
One positive thing, no one was hurt. Another could be, they’ll find out what went wrong so it doesn’t happen (that way) again. However, do note that military operations and even training can be dangerous. Folks tend to use humor to lighten the mental load, so to speak.
Damn straight it was!
When your every move is defined by regulation, custom, local orders, or the grand plans of people totally ignorant of what they might entail, watching one of those plans turn brown, without any injuries, can be a real morale boost.
Real question should be Why in hell would someone deliver several 130 loads of Hummers by parachute, into open fields, when there are perfectly good runways all over the landscape?
If, as I suspect, the answer is a training exercise...didn't they simply relearn that airdrops are going to see something like 10% failures under the best of conditions?