This look likes the device (not a Laddermill but rather stacked rotors with rope drive transmissions, drawing reproduced below) related on Ideas for scaling up AWES based on a tethered airborne rotor driving a rope drive - #57 by PierreB :
@dougselsam 's observation was:
I think its speed is more or less the tether speed of a yo-yo system, i.e. about 1/3 wind speed.