As an example in the Gimbel video [1], he concludes the a pilot is unknowingly locked onto another ship and what's actually showing up is just the exhaust of that ship. Would the military be unable to determine the presence of another ship in their immediate vicinity? The pilots reference a fleet of such ships showing up on instrumentation, as well as implying unusual aerodynamic factors. These factors are all completely ignored. I would put the probability of aliens as something near 0, but I would assess even that probability as higher than 'another ship's exhaust', even if one may be able to create a similar effect through such. I think the best explanation is simply *shrugs*. It's okay to accept uncertainty.
[1] - https://www.youtube.com/watch?v=QKHg-vnTFsM
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All that said I'm extremely skeptical of these videos and even testimony for a simple reason. All this stuff started coming out at the same time three other things also happened. There was a leak about a bunch of sci-level research supposedly being done by the military. Shortly thereafter the Navy publicly patented it. Here [2] is a patent on an inertial mass reduction tool. A web crawl for the author's name "Salvatore Pais" is an interesting and utterly bizarre. If we were researching e.g. alien technology, patenting it achieves nothing except advertising it to the world. And that's something you'd actually want to keep secret.
This was (and has been) happening also at the time that the US military has began failing to meet recruitment goals, and the endless absurd failures of technology (Zumwalt class destroyers, F-35, submarines running into rocks, ships running into each other, etc) seems to imply there's been a brain drain in the military. I think this is largely just a covert recruiting campaign to get more higher-brow types interested in the military. Come enlist, and build a Stargate! It sounds a whole lot more fun than "Come join us and push ads on people who don't want them." Unfortunately it's also probably completely fake.