Too bad they didn't focus on the ropework (at least once).
I saw a butterfly tie-in with two ropes, and the below
tail led to I'm not sure what (or why). I'd like to see how
they ceased swinging and came back to earth.
(Fortunately, this wasn't one of those *instructional* videos
showing something that was A Bad Idea. Nevertheless, as Dan
Osman showed, things can go (terribly) wrong. --when "do the
math" has great significance!)
*kN*