Ask HN: Looking for a specific video on finite state machines

Hi, Not sure if this is appropriate place for this question, but a few months back I saw a video series about finite state machines on HN.

Tonight I meant to revisit it, but couldn't remember the specific title or anything particularly googleable about the series. The one thing I remember in particular about the videos was the presenter was always changing hats and that the videos were used for instruction at Amazon. Hopefully this is enough information that maybe someone could point me in the right direction?

Thanks.