If anti-grav was a thing 80+ years ago, even in the most secret, clandestine, "black" sites, it would have worked its way into mainstream technology somewhere. If the "brightest minds" legitimately created something almost a century ago, someone else would have piggy-backed on whatever theories led those scientists to their discoveries and made similar ones of their own by now. Science and inventions do not typically happen in a vacuum. In order for anti-gravity to somehow be a thing and yet still be completely unknown in the public eye, the technologies leading up to it would have to have been created in secret as well. So we're talking easily over a century of tightly-controlled research and development and breakthroughs, in multiple countries no less, that have never leaked anywhere beyond rumors and conspiracy theories. On top of that, without introducing new minds to a problem, making a series of breakthroughs is extremely unlikely. Most truly revolutionary breakthroughs come from one person seeing a way that someone else's ideas can be implemented in a new or novel way. Unless perhaps that's how you are going to explain there being anti-grav technology 80 years ago, and yet we still have nothing to show for it but shitty "shapes" in the sky.
Seriously, think about all the applications for anti-grav. Skip the space/air part of it, just imagine cars with anti-grav that simply hovered over the roads, drastically cutting the need for road and vehicle repairs. That right there is billions and billions in savings. Trillions maybe. Factor in that you could probably somehow use it for propulsion too, and not only do we get into truly staggering numbers in savings by eliminating a huge source of fossil fuel use, you have practically solved Climate Change in one fell swoop as well. I daresay we might even be looking at quadrillions in benefits just in replacing all forms of locomotion, but I honestly have no idea how much a quadrillion dollars is either. Even if we only get "assist" type devices right now, anti-grav assisted cranes and forklifts would make construction vastly easier and cheaper. More billions saved. How about the buildings themselves? A lot harder for a building to collapse if you install anti-grav assists every few floors. Billions in savings and potentially vast unknown lives saved. And then bringing space into it, who needs fucking Elon Musk if you can just float the shit up there and back? The cost can't be so prohibitive that you can say we wouldn't ever use it in such meager and prolific ways, since they are (according to you) apparently building test vehicles somewhere with some finite amount of money, right? Not to mention, releasing it to the public ALWAYS results in it eventually becoming cheaper and cheaper. Not to mention better and better.
But no, they are going to keep it locked away in a hidden base somewhere for over a century, because it is such a dangerous technology...yet they are dumb enough to let people catch it on video or even see it. Or perhaps we are simply keeping it hidden because it came from aliens, and that would cause too much of a stir if people found out too...but again, they don't seem to care that, if you go by YouTube, literally thousands of people see the craft every year. Oh wait, I already know this answer, they are doing the whole hiding in plain sight thing, because they know people like me will roll my eyes at people like you whenever you mention it, so they are safe even if it landed right on your front yard and little green men anal probed you, on video.
And not that you'll do it, because I think you post and wait to see the reaction to it before calling us out for thinking you were being serious, but I would humbly request that every "sighting" video you post be preceded by your opinion of it. So that we don't waste time debunking it. Simply posting a video looks like, to me anyway, that you are posting it as evidence of something, whatever it may be. I honestly don't see the point of posting those videos that you don't believe prove a point, unless that point is the one I've been saying all along, that they aren't secret military or alien craft. I can't stop you from posting them, and I wouldn't want to, but I wish you'd tell us ahead of time if we're supposed to take it seriously. It would be different if it were the types of videos Chuk posts, where someone gives a theory, or even speculates wildly and seemingly insanely. At least those you can see that he's posting it because someone might be interested in hearing new theories, even if Chuk doesn't believe them himself. You posting a balloon floating over a city, and not saying that you know it is a forklift balloon, makes us think you really believed it was an Unidentified Flying Object, specifically either some secret government experiment or aliens. So help us out, if you feel you need to post it for whatever reason, at least post that you already know it is a forklift balloon.
Anyway, back on topic: there is no anti-grav technology currently existing anywhere in the world. Prove me wrong.