The patent mentioned seems to be US 7,191,737, which can be seen at United States Patent: 7191737 It looks to me like a rather primitive device for electrolyzing water. The news releases make a big deal of a "new" gas, HHO, without explaining how this is different from everyday H(sub2)O, or water. Maybe it's that Klein leaves the electrolyzed hydrogen and oxygen mixed together, as seems to be described in the patent. In that case he perhaps means HHO to be a simple mixture of atomic hydrogen and atomic oxygen. If it's important that they be atomic rather than molecular (that is, ordinary H(sub2) and O(sub2)), the patent doesn't mention it. In other words - sounds fishy to me.
This stuff pops up every ten years or so. The reason why it disappers is because the proponents usually end up in jail for fraud after a lot of people lose their investment money. It is pure snake oil.
Accept we don't have enough water for everyone, and it is a dwindelling source... (only watched half of video)