One of the first points the narrator makes is that the Beatles didn’t read or write sheet music. The sheet music of their songs that you buy was all produced by people other than the Beatles. McCartney says, “None of it was written down by us.”
They obviously understood chord groups in relation to keys, and of key-changes within their songs. “Reading music is only part of what it means to understand music theory.” They obviously knew how to count beats and measures, including how to count pick up notes. But as Ringo explains, much of their approach to rhythms was intuitive.
George Harrison had a good understanding of chord inversions, and he understood how the shapes work their way up the guitar neck. Their music exhibits a good understanding of applied music theory concepts, though they may not have used the formal nomenclature. Any lack of formal knowledge and training was made up for by the Beatles’ producer and arranger George Martin.
You can point to all of the benefits of reading music, but the fact is that many excellent musicians are non-readers. For instance, Paco de Lucia, the world-renowned flamenco guitarist, says he never worked with written music. Flamenco is one of the most complicated and demanding of all guitar styles. Many famous rock players, like Eric Clapton, don’t read music. The fact is many famous recording artists can’t read the sheet music to their own songs. It’s time for modern music teachers to redefine the concept of “musical literacy” in light of how modern musicians create and perform.