"“in 1967 the Beatles underwent a radical transformation..........the world took notice". They probably took acid. You got to be kidding. You think I spend real $ on some such message played backwards.
The whole world went under a transformation at that time, most of it was due to acid. Around 68 and 69 was when acid was made popular as recreational use. Everyone did it, nobody knew the harm in it. I don't think the Beatle's put messages backwards in their songs, just like Stairway to Heaven does not have subliminal messages when played backwards. People like to make stuff up and charge you for it, the only exception is crop circles. Those are free.