Complex sentence: It was originally planned for the band to appear as themselves, but under heavy "aging" make-up, to represent themselves in the future; but their manager, Brian Epstein, objected to them appearing on the programme.
Split into simpler sentences: It was originally planned for the band to appear as themselves, but under heavy "aging" make-up, to represent themselves in the future. However their manager, Brian Epstein, objected to them appearing on the programme.