Jammin' the Blues is an Oscar-nominated short from 1944 that is basically 10 minutes of improvisational jazz played in one long jam. Marie Bryant sings "The Sunny Side of the Street" at one point for the film's highlight then jitterbugs with Archie Savage to bring this most entertaining "jam session" to its exciting end. The director Gojn Mili was a photographer and that experience shows in some of the double exposure shots of some of the musicians that makes this one of the most innovative angles of the '40s. According to some notes I read one of the musicians was white and had to be filmed in silhouette in reflection of the social attitudes of the time. What a shame. Still, this most unusual film of the time is available on YouTube so if you love jazz, I suggest you seek it out there.