it’s not moving fast it’s closer to the camera, look at the middle image in the graphic I posted, at 10 feet from the camera you only have to travel 10 feet from one side to the other and the camera would no longer see you. while a 100 feet from the camera you have to travel 100 feet, it is not going fast, you just see it for a shorter time giving the impression that it is moving fast. if two birds were flying perpendicular to the viewer from left to right at the exact same speed as each other, one is 10 feet from the camera one is 100 feet from the camera the bird 100 feet from the camera would travel 45 feet across the screen before the bird 10 feet away even appeared on screen the and it would remain on the screen several seconds after the closer bird left the frame.
there is a bird at :53 seconds right to left low between the rocket and the tower to the right of the rocket. there is a bird at :54 seconds that starts low near the middle going right to left then loops back to the right, another bird at 1:01 low from left to right, 1:09 one in the back ground right to left between the two towers to the right, immediately followed by the fast one right to left, another bird at 1:11 left to right level with the top of the towers, another bird at 1:12 to the left of the rocket travelling left to right and and increasing altitude
also instead of watching at 1/4 speed LISTEN at normal speed, insect and bird calls, until the explosion
https://www.youtube.com/watch?v=_BgJEXQkjNQ&t=78s