As a demigod, I like to think Pirithous would have a certain level of grace when it comes to his movements. A supernatural level of coordination, when it comes to anything athletic. But a person who has never danced would have a more difficult time capturing and following the steps, than someone who has had his own history of dance in his own culture. I have no trouble believing that Pirithous would be familiar with women-as-dancers, trained for entertainment during feasts. But what about the men? How and when did they dance?
My cursory research so far indicates some references in Homer to ancient dances during feasts and relating to battle, which makes it pretty fair game, since the age of heroes is kind of one of those times that has a certain level of fluid and mish-mashed history, but I'll want to do a bit more exploration into it before I settle on any concrete answers. And as for modern Greek dancing -- youtube videos to the rescue!