Apologies if this has already been mentioned-I don't have time to look right now.
PBS Home Video Pionners of Primetime: Vaudeville Headliners. Radio Superstars. Television Legends. 60 min 2005
[you can Google the title for a picture of the cover, etc.]
Discusses the progression of some stars from Vaudeville to radio to TV
through interviews and filmclips. Featured are Steve Allen, Milton Berle, Sid Caesar, Sammy Dvis Jr. [in a clip with his dad], Buddy Ebsen, Bob Hope, Rose Marie, Donald O'Connor and Red. Skelton.
Although Benny isn't featured as the others, he is mentioned at least three times and clips are shown.