Your last paragraph pretty much sums it up. AI on harder difficulties is pointless, I find. If you treat it like a human opponent you will get destroyed because it basically knows what you're going to do.
Sometimes I fight on hard difficulty thinking it will help me improve at the game, but I don't think it does tbh. Even that can be annoying, so I don't play single-player much unless I'm literally new to a character and want to just get used to doing their strings etc. Then I'll just play on medium.
Nice video though !