In the words of uploader and co-director Ed Seeman:

This three minute film was created by Frank Zappa and Me in the late 60's to illustrate the art of UNDERGROUND MERCHANDISING of his album FRAK OUT! [sic] It was the begining of our filming relationship that lasted two years and became the initial shooting for UNCLE MEAT. This opening was shot at the Garrick Theater in Greenwich Village.
I did all the shooting for the next two years with a silent camera so that Frank could score it himself.
To read the whole story check out my Zappa web site at www.edseeman.com/zappa