There was a discussion on one thread a short time ago about playing two handed piano and letting the accompaniment follow. This is a good demonstration of how well it works and straightforward this is. This is probably his default way to play the arranger.
As far as how good is he - well to the many people playing arrangers who are still developing their skills, this may sound impressive. But in all truth, this is about the absolute minimum level I would expect from someone playing as a professional. This kind of showy ragtime stuff is pretty simple and I didn't hear any evidence of exceptional musical talent. That's not to to say he maybe couldn't do it, but he is certainly not showing it here. Maybe he sings as well.
Mike