Morecambe and Wise say they are "bored stiff" by cult comics Monty Python in a newly discovered TV interview.
The comedy legends made the comments on a student station in Norwich in 1973.
Eric Morecambe said the ensemble delivered "university comedy... and I'm afraid that a lot of it is very unprofessional".
Monty Python member Sir Michael Palin said he was "a little hurt", but "intrigued", having seen the footage.
The double act were interviewed for University of East Anglia (UEA) TV station Nexus while backstage at Norwich's Theatre Royal during a four-show run.
Morecambe and Wise were huge stars of the era and their TV shows could pull in more than 20 million viewers a week.
At the time, the duo were BBC One stablemates with Monty Python, whose mould-breaking, surreal and subversive Flying Circus was met with shock and acclaim.
During the interview, Morecambe - who died in 1984 - said he "doesn't understand" much Python material.
He went on to joke he liked "parts" of it, particularly "the opening and the finish".
"It's the little bit in the middle I don't like.
"I'm afraid that a lot of it is very unprofessional. And this irritates me, being a professional," he said.
"But what does make me laugh, really makes me laugh. And what doesn't make me laugh bores me stiff!"
Ernie Wise revealed he did "like Monty Python", but felt their shows often contained "five or six minutes of utter boredom".
"And then there's three minutes of very funny and then another eight minutes of boredom," said the comedian, who died in 1999.
This generational clash was revealed in a clip of student footage, found during the making of a BBC Radio Norfolk documentary on the Nexus station.
Nexus ran from the 1960s to 2009 and was mainly broadcast on a TV in the UEA's student foyer, before becoming UEA:TV and streaming online.
The incomplete interview clip, lasting two minutes, was put on a compilation tape in 1983.
The VHS tape was kept in Nexus' studio until at least the early 2000s, when former station member Paul Hayes, now a BBC radio producer, made a duplicate copy. He only digitised it earlier this year.
The footage has now been shown to Monty Python's Sir Michael, who remembered watching the duo in pantomime while growing up.
"It was a very interesting little interview," said Sir Michael.
"Though the quality wasn't great, you got exactly their feelings.
"I wasn't too surprised - I felt the way they talked about us, and the way they talked generally, was rather nice."
Sir Michael said it was unusual for comedians to comment on one another so directly at that time.
"People in the same sort of business were very careful about what they said about somebody else," he said.
"It was quite nice that they just relaxed. And it's most interesting what they say, because I think it's what they meant.
"It didn't seem particularly savage - but on the other hand, it was very clear what they felt."
'Over their head'
Morecambe's son Gary said his father's opinion "wasn't news to me because he told me that about 50 years ago", but he added that Eric "adored" Michael Palin, John Cleese and Eric Idle "as people".
Mr Morecambe said: "But they [Monty Python] weren't really designed to be family entertainment.
"It's a very different form of humour that they were having to answer a question about because they came from a music hall background.
"It's a little bit difficult to then see their own form of professionalism against a more intellectual form of professionalism - maybe it just went over their head a bit.
"There was no bad feeling - it was simply an honest question being answered honestly."
Louis Barfe, author of a recent biography about the pair, was also shown the clip. He said it was unusual to get even a semi-serious answer from Eric and Ernie to an interview question.
"It was slightly tough getting a serious answer out of Eric about anything," he said.
Student Colin Webb, then 25, carried out the interview for Nexus and remembered questioning them about Monty Python.
"They actually said a few things in even that small clip that I haven't really seen them talk about much elsewhere - namely, comedy that was going on at the time," he said.
"That delivers something really rather surprising and refreshing."
Following his degree, Mr Webb went back to his career in publishing and ended up working on a book with them. He said he was "delighted" the footage of their first meeting had been found.
Prof Keith M Johnston, from the university, said the footage was an "amazing archive find" that he hoped would inspire the next generation of journalists and producers.
"For UEA student journalists to get an interview with Morecambe and Wise in the early 1970s, particularly one where they pass judgement on the new wave of comedians like Monty Python, shows the talent and dedication of our students," he said.
Nexus: Norfolk's Forgotten TV Station can be heard on BBC Radio Norfolk at 13:00 BST on Monday, 30 August 2021 and for 30 days afterwards online.