They never cease to amaise me those trials guys, it's a pity it's not as popular as it was in the 70's. They always seem to be out there for fun.
Ditto for me too.
I, like Yamaha of the 70's, thought and predicted that trials would 'take off'. Why it didn't I'm not so sure. Trials has a number of advantages. A few pallets, a few pipes and rocks, I could set up and change a practice circuit in my suburban back yard and practice everyday making less noise than your average lawn mower.
And as you say, their skills are amazing.