We can only speculate precisely because everything was classified. The stuff the Pentagon de-classified is heavily redacted, including the videos.
Some of the videos are obviously not any sort of UAP. It's pretty clear the 8-pointed star thing is a paraglider, and the sun is causing a very common star-shaped refraction on the lens, and the white shape-shifting one is obviously a bird.
I think releasing videos of since-identified objects is intentional.
People are posting old post-space-travel videos of interviews with former astronauts, NASA workers, Pentagon spokes-people, presidents and advisors to presidents, and they're pointing out the stunned affects and hushed tones, and, in some cases, undertones of fear and unreasonable stress.
A handful of insiders from the early-ish days of earth's space exploration programs and increased UFO sightings are claiming that Aliens have indeed made contact with leaders of certain countries, and told them they MUST keep their existence top-secret, and if they don't, earth is doomed. Something is going to happen, and our ignorance of these Aliens' existence is vital to earth's survival.
A former advisor to President Eisenhower claims that Eisenhower was so stunned and shocked by information given him by an Alien source, he became ill for days, cancelled a bunch of press conferences and public appearances, and called the Kremlin.