There is no technical data on the rigidity. The areas they show are classic areas for lightening wheels by removing unnecessary weight without compromising rigidity. They don't talk about reducing spoke cross section or changing the material composition.
Put the sucker on a stand, and put some lateral and torsional forces on it.
The tires tell me they were going faster and overdrove the corners, not that the wheels were flexing. Where is the lateral g and speed data with any detail to be useful. A cheap G-tech Pro/R would have given useful data, something like Scott's GPS/accelerometer would be even better.
This is an advertisement for these Enkei wheels, not a useful analysis of weight vs. rigidity IMHO.