...Identify all the musicians in this clip from the movie A Song is Born. I'm ashamed to say that I'm having trouble identifying a lot of them other than the obvious ones, like Benny Goodman and Louis Armstrong. And a commentor at YouTube says that the drummer is the young Louie Bellson.
A Song is Born is probably one of the most pointless movies ever made. Only seven years after his successful production Ball of Fire, Samuel Goldwyn brought back the same director (Howard Hawks) and cinematographer (Gregg Toland, in one of his last films before his untimely death) to film almost the exact same script. The only differences were the cast, the use of Technicolor, and the fact that the subject of linguistics was changed to that of musicology -- allowing for a lot of cameos by jazz musicians. (Benny Goodman even got to play one of the professors.)
Hawks did the movie strictly for the money and objected to being forced to use Goldwyn's then-favorite leading lady, Virginia Mayo (it's too bad they didn't get along, because Mayo later proved herself to be good at playing slightly trampy characters; she seems kind of lost here, probably because Hawks isn't giving her much help). Danny Kaye was very badly miscast in the part originally played by Gary Cooper, and there was no opportunity for him to do any musical numbers. The movie mostly has value for having so many jazz musicians in it in glorious Technicolor, which obviously doesn't come through very strongly in this faded-looking clip.