This is from Sun Valley Serenade (1941) [IMDb]. Previously featured from the same film: In the Mood – The Glenn Miller Orchestra. The man at the piano is John Payne, famous for defending Santa Clause as Fred Gailey in Miracle on 34th Street. The admiring girlfriend is Olympic Skating Champion Sonja Henie.
When Phil Corey’s band arrives at the Idaho ski resort its pianist Ted Scott [Payne] is smitten with a Norwegian refugee he has sponsored, Karen Benson [Henie]. When soloist Vivian Dawn quits, Karen stages an ice show as a substitute.
Ice show! Sonja Henie! Box Office Boffo! Just like all the movies featuring Esther Williams ended up with her swimming.
But never mind all that. Here’s the razzmatazz.
I Know Why (And So Do You) – Sun Valley Serenade HD 1941
vegas1a – Nov 1, 2011 – 5:27
Glenn Miller, with Lynn Bari (dubbed by Pat Friday), John Payne, The Modernaires. As if a medley, this leads in with Moonlight Serenade. Music by Harry Warren, lyrics by Mack Gordon.