Here’s the piece of text from the biography “The Pythons Autobiography by The Pythons”:

Terry Jones:
“We just kept on re-editing and cutting it and trying to make things work. […] But before LA, I suddenly got cold feet about a sequence in Castle Anthrax, where Zoot turns to the camera and says ‘Are you enjoying this?’ Then you go to the Constitutional Peasants saying, ‘Get on with it!’. […] Then the scene goes on and I just got worried about this bit. We were going off to LA and they were actually going to cut the negative, but we were told that when you cut the negative you lose a frame, so once it’s cut you can’t change it. At the airport I was conferring with Terry, saying ‘What shall we do?’ In the end Terry and I agreed to cut that bit, so we rang up the editors and told them to cut it. Then of course we got to LA and I think that got one of the best laughs in the whole film. Since then we’ve put it back into various video and DVD versions and the film is much better with it.”