I have the same fan, I'll love to control it with esp32.
Is he using 3 relays to trigger on/off, rotation and speed? Also, from what I see, he is not detecting the previous state?
I was wondering the same - I re-read it a couple of times and he only seems to be concerned with turning it on and off. I can see where speed would also be useful and I'm sure it's just a matter of using more relays. State is another matter - but it looks like it does have a least a few LEDs that are on when it's working - a voltage probe across one of those LEDs or another similar point should be pretty easy without having to get near mains voltage.