Just watched this one on the Gold Diggers of 1933 DVD which means this was probably part of The Busby Berkeley Collection boxed set. Various people which includes directors John Landis and John Waters discuss the making of the legendary Warner Bros. movie musical which got together many of the cast and crew that would subsequently collaborate on others for the studio in the next several years. Darryl F. Zanuck, who was head of production at the time, is also mentioned as the one responsible for bringing Berkeley to Warners after Busby's previous stint at Goldwyn Studios impressed him. Also mentioned is Gower Champion's 1980 Broadway production and how he did a tribute to Berkeley despite the whole thing being confined to the stage. In summary, 42nd Street: From Book to Screen to Stage is a wonderful account on this innovative production's impact to the screen musical.
