The quality of this explanation is stunning. It is the first time I’ve seen FFT explained such that the complex roots of unity are an obvious solution, and not some convoluted math with no clear origin or purpose.
I know video submissions are not as attractive as articles, but I highly encourage you to check this one out.
I haven’t watched the video yet, but I’ve saved it in my Watch
Another video that I liked regarding FFT -
Ah, I’ve seen this one. Always good stuff from 3blue1brown. Though that’s about the Fourier transform in general, from a mathematical perspective.