This is not what the pilots saw and it was daytime.
Here's another (personal) theory: the "UFO" is actually the result of the jet's own laser weapon/defense system which is why the pan rate is so consistent in the videos - i.e. it's aimed by the pilot himself.
See this article:
https://www.cnn.com/2015/12/17/politics/us-air-force-laser-f...
The specific "tic tac" appearance may just be what the effect ends up looking like - see the picture in this article for a tic tac-looking laser plasma ball: https://www.slashgear.com/super-powerful-laser-creates-plasm...