[exporectomy]

I think this is the number one reason for UFOs being judged as aliens or even as flying objects at all. People don't realize that that if you have no idea of the distance, size or speed, then you can't even attempt to estimate any of them and seemingly impossible things happen. Planets look like balloons, cars look like stars, etc. This seems to be the problem with those military pilot's videos and accounts.

Whenever someone says it was "as big as a ..." or "impossibly fast", they're usually interpreting what they actually saw through their faulty intuition about those things. Angular size like the OP said is a useful observation, but not actual size.

I experienced this the first time I flew on a plane. I was watching the clouds passing by just below the plane and had a feeling for our comfortable speed, then suddenly a whispy bit of cloud in the foreground shot past much faster than I thought we were travelling and gave me a little shock. I then realized the clouds I'd been watching were probably much further away than I'd imagined.