Because it is too far away. Light can not penetrate an infinite distance through the air.
Are you saying that there is an infinite distance of air between Polaris and pretty much anywhere south of the equator?
No, do you not understand the difference between infinite and finite?
I can't say for certain, but it seems to me to be the stars rotating.
I like to think you would know because it makes a big difference. It is hard to imagine a universe with trillions of galaxies and stars spinning. They would have to travel much faster than the speed of light. All we would see is a blur or nothing.
Only if you assume that they are as far away as you have been told.
Polaris is 420 light years from Earth, that is about 2,526,078,719,600,000 miles. The fact is you can't see it at all from Australia because the earth is a sphere. You saw the video.