Before the adaptation Mary Poppins was a gigantic hit, Walt Disney himself had to convince author P.L. Travers that her story belonged on the big screen. This untold history gets its own adaptation with Saving Mr. Banks, arriving in limited release December 13 before expanding nationwide December 20. Walt Disney Pictures has released four featurettes that give fans behind-the-scenes footage and interviews with cast members such as Tom Hanks, Emma Thompson and director John Lee Hancock. We also hear from Mary Poppins composer Richard M. Sherman, who tells his own personal stories about interacting with Walt Disney.