Well now I'm completely confused.

You have a hydrogen/oxygen generator. Since the chemical composition of water is H2O, then the gas given off is both hydrogen & oxygen.

It does not actually create a volume of gas that is greater than the water it is made from because that would crate a positive pressure [higher than atmospheric] Instead it must actually create a volume of gas that is less than the volume of water it is made from, thereby producing a negative pressure [less than atmospheric] & that is what would make a plastic bottle collapse inwardly or 'implode'. [according to the info that you provided]

So now this unstable & combustable hydrogen/oxygen gas, which is at lower than atmospheric pressure, is drawn into the carb via the distributor vacuum line.
It must be remembered that this is ported vacuum & is not operational at all when the engine is idling. There is also no appreciable vacuum at this point at high power settings & high loads [steep hills] so little or no gas would be drawn into the engine at a time when it most desperately needs it.
Also remember that the vacuum advance function relies on a vacuum signal to work, but if this vacuum signal is being killed by the inflow of gas through this port in the carb to run the engne, then the vacuum advance canister can not do it's job & the engine is running with spark retarded from the optimum position.

Next, we see that the engine is reved, [it's running on petrol/gasoline] & this combustible gas, at less than atmospheric pressure remember, is drawn into the engine via the tiny little drillings in the carb that are intended to provide a passage for distributor vacuum.

The engine still runs, but burnt hydrogen & oxygen gasses are re-formed back into water again which is seen at the tail pipe.

I have a couple of questions.

Since you could draw raw water into the carb, hell, you could even suck in a milkshake via the tiny little vacuum advance drillings & have the engine still running, what was it that was actually being demonstrated here?

If this system is to work, how do you match the production of the unstable & combustible hydrogen/oxygen gas to engine demand?

If production of gas is not matched, how do you safely store such a dangerous fuel [the gas] keeping in mind that the combustible element [the hydrogen] already has the oxidising agent [the oxygen] mixed in with it?

On combustion, does the gas expand & produce positive pressure, or does it implode & form a negative pressure in the combustion chamber?

How do you throttle the engine when running exclusively on hydrogen/oxygen?

Remembering that the gas is produced in a container with only one outlet, & the interior of the container is at less than atmospheric pressure [this is why we need glass jar & not a plastic one rememeber] how does the gas get from the jar to the carb?
If it is at lower than atmospheric pressure, it would tend to suck air into the jar, not transfer gas to the carb.
Simple pressure differential at work here.

It takes electrical power to convert the water to a gas & this is provided by the alternator which in turn is powered by the engine. If it takes more electrical power to convert the water to gas than the newly formed gas can in turn convert into additional power, then we have a net loss.
How have you measured the power gains?

The answers to these questions may really fuel my interest.