Okay, this wasn't a good idea from the start. What mystifies me even more is how poorly it was executed.
Why didn't they use a weak link for the practice?
Why did they set it up so tension in the rope created a huge rolling moment?
Does the cargo hook even release when it is side loaded that much?
I'm not condoning this type of flying, but even those who take such risks (ie stuntmen) enter it with professionalism and caution to avoid the loss of lives and millions of dollars of equipment.
Darwin was right.