About the film
Upbeat in Music is a 1943 short film produced as part of The March of Time series distributed theatrically by 20th Century Fox. The film has significant history as being early film appearances of Frank Sinatra and Perry Como. The film also features footage of Glenn Miller in uniform as a captain in the United States Army Air Forces leading the U.S.
Army Training Command Band.
From the film's Wikipedia article (CC BY-SA 4.0).