Co-founded by George Balanchine in 1948, New York City Ballet is considered one of the best dance companies in the world, and the foundation of ballet in America. Correspondent Serena Altschul talks with the company’s current leaders Jonathan Stafford and Wendy Whelan, and with legendary dancer Suzanne Farrell and principal ballerina Megan Fairchild, about NYCB and its affiliated School of American Ballet, and how, at 75, the company is catering to an increasingly younger audience.