Dynamic or motion speed/Texture2D

Hi all,
i have standard setup: camera > BackgroundSubstraction> moving silhouettes of the persons on transparent background.
What is the best way to get value of dynamic of motion/speed of movement?
Attached is the patch using MotionKey(EX9.Texture Filter) and Average(EX9.Texture Analysis).
I wonder if someone used another approach.
cheers, dimi

MotionAverage.v4p (12.0 kB)