I don’t have the math chops anymore but I would like to see the actual calculation for 1000 yards and less than 2 second flight time.
Well, let's see...
Earth rotates 360° in 24 hours, which is 86,400 seconds. Old-fashioned division gives us 0.0042 degrees/second, or (interestingly) fifteen seconds per second, although the first "second" is arc-seconds, and the second "second" is actual seconds.
If you take my meaning.
Anyway, during a two-second flight time, Earth moves under us 0.0084 degrees. At a distance of 1000 yards, and if you're at the equator, that's a distance of
which is a bit more than five inches! 5.27788 inches, to be more precise.
Of course, as pointed out in the article, that "movement" will be "up" if you're aiming due West, and "down" if you're aiming due East. If you're aiming North or South, there's no effect at the equator.
If you're at the North Pole, and you aim in any direction, you're aiming South. In that case, the 5+ inch error accumulates left-to-right, so you will hit a spot 5.27788 inches to the right of your aim point. The direction would be reversed at the South pole, of course.
At any point in between, you've got to bring more sines and cosines into the situation.