Page 16 of the manual states,
"Auto motion plus ( off / clear / standard / smooth / custom / demo) enhances motion in fast moving scenes) The info on your TV displays the resolution and frequency of the incomming video signal(60hz) this display frequency is not what the TV is displaying by using the auto motion plus function"
Doesn't make a whole lot of sense to me. could have lost something in the translation.
I'd e-mail someone at samsung.com for clarification if needed.
Looks to be automatic, what happens when you play a Bluray disk as the signal source.