It's not called Prairie Chicken Dance because the name is cool. There is a very elaborate story dealing with the Prairie Chicken both with the Blackfoot and the Cree. The first video link is the mating dance of a Prairie Chicken, which is how Blackfoot Chicken Dancers primarily try to imitate, especially during the loud and fast beats of a Chicken Dance song. Dancers imitate the motions of the Prairie Chicken when a Chicken Dance song starts or has sneak-up beats in it.
Prairie Chicken Mating Dance
Video by the Blackfoot Tribe on Chicken Dance