According to the YouTube caption,
Jammin’ the Blues is a 1944 short film in which several prominent jazz musicians got together for a rare filmed jam session. It featured Lester Young, Red Callender, Harry Edison, Marlowe Morris, Sid Catlett, Barney Kessel, Jo Jones, John Simmons, Illinois Jacquet, Marie Bryant, Archie Savage and Garland Finney. Barney Kessel is the only white performer in the film. He was seated in the shadows to shade his skin, and for closeups, his hands were stained with berry juice.
The movie was directed by still photographer Gjon Mili.