I don't really get what you are trying to say.
The video showed an idiot maintaining that he could get something for nothing and we were being forced to consume greater volumes of fuel because engine come fitted with carbs burning a liquid because he has no idea how a carb works
He then seemed to be aserting that his device was releasing some sort of "magic vapours" locked within the liquid.
He then followed up with a bog standard conspiracy theory.
You are waffeling on about LPG engines ( I have been using them for 30 years ) then confusing work with power and trying to connect fuel consumption of 2 strokes in there.
None of this was part of the video.
The bottom line for any engine is there is a finite amount of energy in any fuel.
The trick is converting the chemical energy ( measured in Calories or Jules ) into mechanical energy.
The problem with any combustion engine is you are converting chemical energy into heat energy first.
Then using this heat energy to push a piston / turbine to convert it into mechanical energy and electrical energy.
Every conversion is not particularly efficient and every conversion also looses energy through unwanted or unused by products.
Cooling an engine burns up a lot of energy that was originally converted into heat but can not be used by an engine.
This is why in the early days air cooled engines got more useful energy than water cooled engines despite being less efficient.
Perpetual motion is a myth.
As is the garbage spewing from the mouth of the video presenter.
Fuel economy is a totally different matter again.
You could run your car on a 5cc deisel toy aeroplane engine and get 200 mpg.
The problem is it will take all day to go 5 miles.