content: Grounding is exactly the opposite of what you want. What that guy's doing in the video is connecting himself to the HV line while very well insulated from ground - his whole body is at 500kV AC, the same voltage as the line, for the whole time he's hooked on to the line. That's why the line isn't zapping him - because there's no difference in voltage. So generally a drone is fairly well protected from getting zapped, because it's insulated from earth. There's nowhere for the voltage to 'go' so there's no current through the drone. However, if it gets too close to the metal structure of the pylon (which is earthed), it could act as a bridge between the power line and then it'd get fried instantly.