Learning to slackline requires the patience of a monk who grew up with four older siblings. It takes approximately 1,000 tries just to balance on the thin, squirmy rope. Then you have to try and take a step, which takes at least 3,000 more tries. By the time you can make it halfway across the rope, you'll be in your mid-30s.
It's impressive enough that these guys know how to slackline in the first place. But to further prove they're superhuman, they decided to gather up in a couple hot air balloons, soar up high enough for an astonishing view of the mountains, and then slackline. It's so bold we don't even mind that no one was able to make it across successfully. When they fall they just stop the slacklining portion of activity time and begin skydiving.