John Lennon and his wife, Yoko Ono were guests on the Dick Cavett show on 11th September 1971. This was Lennon's first interview after the Beatles had split. The Lennon's discuss their artistic collaboration, with reference to Yoko's work. It contains some footage of their film work and previews the release of Imagine. There's some warm up chit chat at the beginning that may be skipped.
John described Yoko as "the world's most famous unknown artist: everybody knows her name, but nobody knows what she does."
The first interview continues here
The Lennons appear at approximately 27 mins into the video.
Yoko Ono on Wiki