“Winners from three age-based divisions, chosen from some 90 hopefuls from 23 countries, took to the stage with fellow competitors and professional dancers to spin through excerpts ranging from Perrot’s “Giselle” to Petipa’s “Swan Lake” and modern pieces including Edwaard Liang’s “As Above So Below” and Margo Sappington’s “Christina’s World,” each of which dancers learned from a video and performed in the competition.”