If he has figured a way to break H2O to HHO cheaply it would be the Holy Grail of fuel. He claims a "fuel burn" of 4oz to go 100mi in a Ford Escort. That equates to 1 oz of water /25mi. If all of the supporting equipment weighed 200lbs and I carried a Gal of water (fuel burn of ~10oz/hr) I would be 40lbs ahead on full fuel usefull load.
I looked him up and what he is claiming is he is mixing the HHO with Gasoline and improving the fuel economy by 30%. He claims the machine in the video can make 1500-1700L/hr (53-60cuft of HHO) for $0.70/hr in vapor form.