This is either a mysterious lighter than air helicopter or a photographer who was able to synchronize his cameras shutter speed with the helicopters rotors.
I still prefer fixed wing aircraft.
Nal located this information from this site:
They do this all the time during maintenance tests. There is a radio source on the helicopter linked to the rotors’ rotational speed, which the camera pics up and uses to trigger the shutter. The technicians can use the video to look at loading and stresses, as well as any deformations. They can use this information to replace damaged or out-of-spec blades.