The video shows the right and wrong way to take crossing shots. Mounting the gun ahead of the bird and pulling the trigger immediately is the easiest, best way to shoot crossers. When shots are as close as these brant are to the blinds all you have to do is look at the beak and shoot.
Riding the bird, that is, swinging with it to make sure, is the best way to miss a crosser. Once you’re on target, shoot. Your chances don’t get any better if you try to refine your lead, they get worse. Your eyes drift back to the gun to check your lead and the gun slows or stops altogether.
The segment with the shooter missing shows that what happens when you ride a target, and it also shows a very common occurrence: you miss by being too careful, then think “oh no, it’s getting away” move the gun as you should have in the first place and make the shot. I’ve done it a million times, and you probably have, too.