anyone?...
persona,I honestly don't see what is so strange ... are you referring to how the octaves alternate with alberti bass in the left hand?
He's talking about how those four measures are repeated strictly sequentially except for the changes he enclosed in the red boxes. It really all revolves around the last note of the measure in the left hand. The first one is on the fifth of the chord, the remaining three are on the root. Personally I have no answer.