Once, I actually did see what this person is claiming to have seen. It was back in 1980, a bright sunny day with some clouds overhead. I was standing near a park with a group of friends and happened to look up. There was this slim, metallic looking thing with a silvery color, flying overhead. It made no sound. I was puzzled, because I thought at first that I was seeing an airplane, with the wings obscured by clouds. Then I realized that it looked like an airplane with no wings, or windows either. It appeared briefly, then went into the clouds, reappeared, still flying steadily. I started to call attention to it, but it had already vanished from sight.
That shape in the video looked fatter than the shape that I saw; I think Duke is correct about what this person has filmed.