is a consummate showman who knows the number one rule of showbiz - the show must go on.
This footage comes from a private corporate gig that Stevie did back in the day, and clearly, that corporation didn't bother to do a full sound/equipment check beforehand. When the legendary performer comes out, escorted onstage by an attendant/bodyguard, it becomes quickly apparent that the electric keyboard set up on top of an acoustic grand piano isn't working properly. Stevie tries several times to plunk the keys and test the acoustic piano underneath as well just to be sure and despite a few techs trying their best to mess with it in the background, the keyboard in question never seems to produce any sound other than the occasional dull thumping and tapping of Stevie's attempts to play on its dead keys, picked up by his vocal mic.
Ever the professional and never short on talent and charm, he instead plays it off by improvising a song about the situation as he plays the acoustic piano instead, making jokes about how it's a good thing he doesn't depend on this equipment for his career or anything. We don't know if the keyboard was ever fixed that night, but there's no doubt the guests had a great time either way.