See engineering challenges documented above and https://brilliantlightpower.com/plasma-video/ and their video archive also they have hydrinos isolated in a test tube and have performed many analytical experiments to measure properties that definitively prove exactly what it is and matches the theoretical predictions.
Videos they make aren't good evidence of anything. Just send samples of one or two pieces that show off these improved physics. It would change the world, make them famous, and let them get them rich off of patents. No need to wait until they have a full working product.
The only reason to hold back so much is that it's not real.
Videos are evidence of the many problems they have run into getting it to work reliably.
One good reason to hold back would be intellectual property/stealth mode development. They have many patents but have had some patents rescinded after skeptics objections about "breaking known laws of physics" as if there is ever a final unimpeachable unimprovable laws of physics.
Even so the theory is openly published and samples of hydrinos are available to qualified parties I understand.
Yes everyone, especially including all the believers, is waiting for the definitive demonstration that makes everyone stop and say whoa, WTF is going on. I envisage something like putting a suncell on top of a mountain and illuminating the whole county at night, but the FAA might not like that.
The "Don't you want a Nobel prize?" argument is a very good way to detect pseudoscience.