and i think the high risk thing is the actual point of doing it this guy likes living on the edge. as you can tell from the what he says at 1:20 in this video:
i've been slacklining for 3 years now and highlines are so badass, i do quite a lot of so called "action" sports, but nothing gets my adrenaline pumping more then walking on a highline!
(ofcourse always with a safety line )