Video: When you smash the previous world record of walking on a highline of 500m -- by doubling it over, walking on the slackline for 1km, you are truly fearless. When you do it in the sweeping mountains of Aiglun, France and walk as if you're not afraid to fall, extreme can't even begin to describe you. That's Danny Menisk and Nathan Paulin. Watch as they both pull off the incredible feat of slacklining for over a kilometre in the video below. Watching them fall and hearing the noises of the rope is just so frightening. Thank goodness for safety lines.