I have never seen a video of it working before though and that always created a sense of doubt . . . . .
Here it is, from Mike at Quanta Magnetics. His more recent efforts are very, very interesting too. If I had the money and time I would have built one of his Resonance Generators already.
How do I know this stuff works?
First, lots of background experience: as a child, mucking around with electric motors, batteries, magnets, etc. etc. It seems that nowadays there are too many children who don't get to experiment with real stuff and so don't have a real grasp of physics - so they equate it with magic.
They might get a computer program that simulates electronics instead and think that will tell them what it is really about . . . . scary.
Then there is the understanding of science, what it is, and just as important what it is not: much of science research is done in the pay of corporate or industrial concerns to improve their devices or at least improve their bottom line, NOT for the benefit of people in general and not for the discovery of new or different ways of doing things.
Finally, there is a clear understanding of reality: science can only discover what is real, and the real universe does not change simply because someone wants it to.
There are an endless series of fake or fail "free energy" vids on YouTube, but this one is not. It is easy for people who have not spent the time and energy to claim things are fake because they could not make it work in their garage - but that does not make it a fake. How many people could make a working electric motor in their garage from raw metal and wire? It really is not as easy as you might think to make devices that work, let alone work long term.
I would point people here to the Mythbusters TV show and specifically the "Gorn Cannon" episode: modern people attempted to make a gunpowder cannon from raw materials, and these were not stupid people either - and they could not even get gunpowder that exploded. It really is not easy unless you have the knowledge, experience and the right resources.
It is painful for me to point this out but I am spelling it out because I am fed up with people who have so little idea of science that they equate it with magic.
The main problem as I see it is that too many humans get all caught up in how great they are rather than giving due credit to the long, hard work of others who have come before. It has been known since at least as early as the fifties that the oil WILL run out, that the environment is getting damaged by all our pollution and that we need to do something about all this or we will end up like Venus - and solutions have been found, but where are they? The only ones that have been put into practice so far have either been half-done or have made little difference because huge powerful interests don't want to change things. Batteries that don't run out don't make profit for that manufacturers so if they were invented they would swiftly disappear.
Have a go: build yourself an electric motor that actually works, just a couple of AA batteries will be enough power - get some real world experience of physics and you might just be able to find something other have missed in their rush to make a fast buck while ignoring the future consequences of a half-arsed invention. But don't expect millions of dollars or public acclaim.