From helvelabs
The Klaus Cam is a slick aerial camera rig invented by Scott Howell of CineMoves out of necessity while filming in Greenland. They were only getting top shots when they really wanted wide-angle shots lower to the ice where no helicopter pilot would dare fly. They came up with the Klaus Cam which is a three-axis, gyro-stabilized head that hangs on a long cable below a helicopter, making it possible for the helicopter to fly safely high above while navigating the Klaus Cam through tight and treacherous surroundings that would be dangerous or impossible to navigate with other types of rigs.
You can view the original video at: Aéro Films
source @nodrick
And here’s a behind the scenes filming of a band playing in the desert. The video is noisy (desert wind or wind whipped up by the helicopter rotors, I would think) but you get a pretty good idea of how long the cable is.