Somebody above mentioned acetone.  How much acetone would you need?--I mean nail-polish remover is just acetone and water, and works fine, but the smell is unmistakable and would require the news-team to be in on the scam.  

Could you cut it to the point the smell would not be obvious?  

Or is it a different technique altogether?  

Consider the radio beam:  If it was tuned to either salt or water, he could not stick his hand in it.  So perhaps he has tuned it to something ELSE in the saltwater that does not occur in the human body.  Or has ADDED a substance to the saltwater.  This picks up the energy of the beam and then does . . . something--which drives off a flammable vapor.  The puzzle is, what and how?  

The goofy smiles of the "university scientists" combined with their total, amazed bafflement (they should not be amazed, whether or not they are baffled) convinces me they are part of the scam.  

The Fates are kind.