In fact anything unimaginable is possible.
I read about a news not so long ago that there were some devices invented, basically attached to your bloodstream that would generate electricity simply through blood flow.

Just looking at that box this guy made, I don't see really much happening if he really is to utilize gravity to generate electricity. He must have some other towel tall devices in his backyard, else it's hard to comprehend how he could use gravity just out of that box.

Every inventions that happened, happened out of accident when inventors didn't mean to create their invention and pointless to mention that they're not asked for their academic degree like we lowly Nepalese attitude point fingers at others when something is about to be created. "They couldn't do it, can you do it?"

If this guy could do this magic happen, he'll create his own theory and our son and grand children would be memorizing his theory in schools decades later. But I'm also skeptical that it would turn out to be cheap stunt to get attention for nothing after all we've seen Tempo conductor who invented helicopter(that can't fly), peepal leaf charger that can't charge anything and such.

Best of luck