Ed,
How do you know the motor's output isn't changing? If they are showing a reduction in real power, it is most likely due to reduced output on the motor.
Show me a test using a motor connected to a dynamometer. Otherwise, it's like the magic disks they used to sell (do they still sell them) that would reduce power consumption of light bulbs ... by half-wave rectifying the power and reducing the light output!
People will always find new ways to sell snake oil ...