A high voltage electric field can move a charged capacitor?! Who knew?!
It's a neat little desktop demonstration, but it's not demonstrating what these people claim it is. Electromagnetic couplings between charged particles are of order 10^27 (10,000,000,000,000,000,000,000,000,000, aka "a lot") stronger than gravitational couplings. Moving a charged object in a strong electric field is old news: that's how CRT monitors, cyclotrons and a variety of commonplace technologies work.
There was a Russian physicist (can't recall his name) who claimed to have discovered a similar "coupling" between electric and gravitational fields. He had an amazing experiment that he wouldn't show to anybody else. He was interviewed by a Wired magazine writer who by admission didn't understand the physics involved. Then, when other physicists asked him how his experiment worked he freaked out and declared that "The Scientific Establishment" was persecuting him.
He finally entrusted the miraculous secret of antigravity to a Swedish graduate student (iirc), who was unable to reproduce the effect in the lab. The guy tried to publish his theory in a small, backwater journal and it was rejected by the reviewers -- he didn't consider alternate explanations before leaping to antigravity, and nobody was sure of his experimental controls since he wouldn't tell anybody. He has since dropped off the face of the Earth, claiming he will return with irrefutable evidence that even "The Scientific Establishment" will have to accept.