On a set that's meant to look like a street, Lynn Albritton plays the boogie-woogie number while a group called the Harlem Dancers jitterbug in this soundie.
Soundies were three-minute films meant to be played on a video jukebox called the Mills Panaram. The devices were installed in bars, diners, and other venues similar to the places you might find a more usual jukebox. From 1940 through 1946, Mills and some competitors produced more than two thousand of these films, many of which featured performers, like Doris Day and Dorothy Dandridge, who would go on to greater acclaim.
I was unfamiliar with Miss Albritton; apparently this and two other soundies are all the recordings of her fine playing.