From the FAQ:
“How does it work?
The G35 utilizes an INTERMEDIATE FOCUSING SCREEN, which is tuned specifically to minimize light loss. It works by passing you image through a 35mm lens and projecting it onto a VIBRATING screen.”
The batteries vibrate the Intermediate Focusing Screen.
This gizmo attatches a 35mm lens to the front of a video lens. Inbetween the 35mm lens and video lens is the Intermediate Focusing Screen(IFS). The 35mm lens projects an image onto the IFS (which acts as a focal plane) and the video camera records the image from the other side of the IFS. The IFS is made of a grounded glass and has to vibrate and/or rotate so the ground glass texture blurs away.
Theres probably a better way of explaining this but I am partially iliterate. hope it helps!