Although I have never heard of him, apparently Martin Block was a famous disc jockey of his day and is featured in several confusing films. I say confusing because all six of the shorts he made ALL have the same title and came out in the same year! The only way to know which is which is by seeing which artists are featured in each one. In this case, the film highlights the most famous songs by Freddy Martin as well as has an interview where Keenan Wynn interviews Block.
As far as the Martin tunes go, the summary mentions two but the famous "Wizard of Oz" tune "Over the Rainbow" is also featured. All of the Freddy Martin pieces are very nice and you see him and his band performing them. The interview is fluff, but also reasonably entertaining. Not a bad little film...and mildly interesting.
