Young Dudley Moore performs Jump.
This, for the uninitiated, is Anglican Chant, like what we do every Sunday at Evensong in the Cathedral when singing Psalms. Well, to different words, obviously!
I have a whole DVD of Dudley Moore and Peter Cook recording their iconic Derek & Clive stuff, and although it's been a while since I watched it I think this is a clip from it.
Please be aware - sound required, and Parental Discretion is well advised. Don't look at it at work.
Thanks to MDB for this.