Not going to lie, I have always been fascinated by the fourier transform, but I had to stop this video after less than 2 minutes in because it went way over my head... "a context you are all familiar with: polynomial multiplication"... um no, I have zero clue what that is, sorry. Also the speaker seems to have some sort of speech pathology that unfortunately bothers me.
I like this 3Blue1Brown video about what he calls the almost-fuerier transform:
www.youtube.com/watch?v=spUNpyF58BY