I’ll count his as a “short film” today just once. Here’s a video from “The Art of Problem Solving”, where Deven Ware solves an advanced geometry problem. I think these videos were made at UCLA; Jack Andraka (Stanford) shared some of them on Twitter about a year ago.
Math teachers, here’s an idea for your final exam this year. I don’t sub for you in the public schools any longer, but my thoughts are still with teachers.
Students, watch the AOPS videos to prepare for finals, or for free-response questions on AP tests.