the link in 267 is better- comes riht up and is cued almost to the slap- the 7 second mark is the start of the slap-
I see what you mean - fingers bent backward. It’s a Hollywood slap. Maybe Smith wanted to embarrass Chris without hurting him.
At first, Chris reacted as if he thought Smith was joking around - because I guess Chris wasn’t hurt physically at all.
Smith’s yelling obscenities after the slap is what leads me to believe the slap wasn’t a planned stunt.