polar alignment emphasised with motion

As I watched AlphaPhoenix's cool YouTube video on his simple barn door tracker (hinge style), I was struck by something he did in the middle. He took a time-lapse of his tracker (and his equatorial-mounted telescope) as they tracked, as they moved in right ascension. And in particular, he pointed north. And then he emphasised Polaris with an annotation.

I thought, this is absolutely brilliant! For the newbie not clear about polar alignment, why to do it, how to do it, where Polaris is, etc. I thought this is amazing. Such a strong visual! And the still image I grabbed from the video doesn't do it justice. You have to see it move!

He does this the first time at the 1:39 mark. And again at the 2:02 mark. More at 5:03. Amazing.

A fantastic video in many ways. He based his barn door on Gary Seronik's, showed the cheapest possible solution for those who want to try it, he explained it all clearly, and he is enthusiastic. But its his annotations that knock it out of the park for me.