My opinion prior to watching the link having watched "Get Back" at least twice and the fact that Beatles music has been part of my entire life:
Paul knew theory and piano and could pick up any instrument and master it. John knew music theory and played some hand aching chords effortlessly. Ringo is an incredible drummer and his subtle grooves were just that and perfect.
I was taught piano, cello, french horn, trombone (not the rusty variety), and trumpet growing up. I mastered nothing, but when I first picked up a guitar as an adult I couldn't figure it out at all. I posted on this board several times about my frustrations in trying to relate a guitar fret board to a piano keyboard. The answer I received several times is that they are completely different animals from that point of view. So, I think George undoubtedly knew complex guitar theory. It's just a mind fuck to translate to a piano keyboard. Easier to ask Billy to translate.
Now, I'll watch this shit and see if my opinion changes.