Singer, bandleader, pianist, talk show host. He's also decent actor, though I don't know if he's acted in anything lately.
I give him extra points on the musical front because he does nerdy stuff like slowing down and speeding up an improvised melody in the right hand while a syncopated left hand retains the same tempo. He's famous enough he could probably just play something showy like Liberace and get away with it.
Here's an earlier submission that explains it a bit: Friends don't let friends clap on 1 and 3.
(Come to think of it, this seems very song-dependent. For instance, I definitely find myself clapping on 2&4 to "Thriller" and "I Heard It Through The Grapevine". But I think I'd still clap 1&3 to some of my favorite classic rock and metal songs. Also, I felt 1&4 pretty strongly in that Harry Connick Jr. clip. Maybe they're just clapping too fast: if they were only doing half the claps, I think 2&4 would feel more natural.)
https://www.youtube.com/watch?v=sOnqjkJTMaA&t=5m0s
Curious what you mean by half the claps? Would this involve clapping only on every fourth beat, only on every second beat, or am I completely misunderstanding?
I remember Bobby McFerring being capable of playing audiences in surprising ways too. (funny since Youtube suggested him on that HCJr video)