I call BS. His demonstrations look more like a steam punk themed Magician's tricks, with out the scantily clad assistants. I'd be more impressed if he wore a tophat and waved a wand.
Lets ignore the fact that he's been to prison for fraud in the past, or that this is his M.O., The science just isn't there. But the skill of the trick is interesting.
Essentualy, Like any good Magician, he gives you a story, filled with terms you don't fully understand, but with a remarkable and clever outcome (In a far away land ancient monks knew the secret of...)
. he then shows you a device, that he demonstrates some of basic parts of. ( Just an ordinary box, nothing remarkable about it at all, but Observe!...)
He's very good at showing slightly more than your attention span wants to see, and giving you an information overload so that you don't notice what he didn't show you. (You know, he never showed the bottom of the box, and it never came of that funny table... )
He then preforms his Trick, and you see exactly what he described you would see. Humble beginings, with dramatic and supprising results that exceed your expectations. And then like any good street preformer, he doesn't ask for money, but he lets you know that he appriciates it as the hat is passed around. ( The investors have been most gracous, thank you, thank you.. )
Proving him a fraud would be difficult based on the information available, but recreating his demonstration wouldn't be, if examined like a magic trick.
An interesting article from someone in his field who met with Rossi: http://blog.newenergytimes.com/2011/10/30/noble-aspirations-are-not-enough/
Buy the ticket, take the ride.