Class B external load. We do it with singles, the 500 is a pretty good machine - note how steady the line is when he delivers the hook to them at the top of the tower. They were using the proper approved harnesses, double clipped, and there was no remote hook on the end. As for the whipping 'em around at the end of the longline, ....yep, aircraft probably wasn't wired for FDM.
Nowadays, "riding the hook" is frowned upon, but used to be pretty standard in the logging shows I worked on, especially on the cedar shake block sides.
Here's a write-up, some made it some didn't, and sometimes the odds of helicopter flying in general caught up with you.
http://www.truth-or-consequences.com/misc_stories/hook.htmlIn fact OSHA even had to specifically address this behaviour in heli-logging in Oregon
http://www.orosha.org/pdf/rules/division_7/div7_m.pdf**Corrected reference to Class of external load.