This thing sounds a lot like the old "Brown's gas" craze, which was simply hydrogen generated by electrolysis of water. The problem with it, as is the problem with hydrogen as a fuel in general, is that the energy density--the energy derived by burning hydrogen--is relatively small. And, you can NEVER get more energy out of the fuel than you put in to create it.
This sort of thing goes on all the time. A guy comes up with some idea, claims that it works, shows some kind of demonstration that doesn't really prove what he claims--whatever that is--and then tries to market it. And, what EXACTLY is the guy claiming? Does he claim that this is an energy SOURCE, which means that he gets more energy out than is needed to create it? If so, this is an out-and-out scam. If not, then what's the advantage over hydrogen generated by electrolysis (if, indeed, he is generating something different)? Don't count on Fox News to ask questions like this.
Also, what is the difference between HHO and H2O? This is chemical nonsense.
The thing to remember is that the burden of proof is on the guy making the claim. Until there is some genuine proof that this is more than simply hydrogen, I don't buy any of it.