Not that particular one but I have noticed more "GEET" devices around
(note I don't vouch for the video just happens to be one of many)
GEET does work, the catalytic converter carburator is a very very old idea, even the big boys were playing with it before fuel injection.
I have a feeling GEET or a Catalytic carburator would have been a much better path for FE than fuel injection.
Contrary to popular belief all of your fuel DOES NOT burn in the motor but instead during the exhaust cycle and even as it exits the motor. That is why we have a CAT and depending on motor load the amount can be rather large because gas has a lot of heavy chains in it now days which usually do not completely burn in the motor. Having experienced a vehicle with inop CAT compared to an Antique that came that way I have to say the antique was less gassy smelling and the tip of the exhaust pipe was white, the tip of the OBDII minus cat was black and messy, a classic way of knowing it isn't running at top efficiency.
A CAT ahead of the motor allows all of the fuel to be uniform entering the chamber and for more of the fuel to burn.
How much of an economy gain this can cause is conjecture but I would argue its significant enough that it should be implemented in some applications, especially large stationary motors.
Cheers
Ryan