A fast rope hangs from the gantry and extends from the side/rear/hell hole of the aircraft and each man slides down it like a fire pole. There is nothing for each individual roper to rig, feet and hands on the rope and away you go.
The doors were likely open? Impossible to fast rope from a UH-1 with closed doors.
Understanding how VBSS and fast roping work are elementary to understanding how this accident could have occurred. The odds for something going wrong when you are on the rope, the aircraft moves off target (ships deck), you find yourself now over open water, 30 to 50 feet above the surface and wearing 50 to 80 pounds of gear,,,,,are far from astronomical and are in fact in the "pretty damn good" range.
Edit to add: VBSS = Visit, Board, Search, Seizure
Great post. Good info