For three decades the Guggenheim Museum has hosted Works & Process, a popular lecture-demonstration series in which artists discuss works in progress. For audiences, it pulls the veil off the mysterious creative process (to some degree). In "From the Works & Process Archives: Three Choreographers Celebrate," Ms. Armitage, Mr. Keigwin and Ms. Tanowitz present footage from their time with the program and discuss the experience with Virginia Johnson, artistic director of the Dance Theater of Harlem.