Complex sentence: Harrison appears in a range of Beatles-related costumes while miming to the track--starting with the Hamburg-era black leathers, followed by 1963 mop-top wig and grey collarless suit, and soon changing to the iconic "Sgt. Pepper" uniform.
Split into simpler sentences: Harrison appears in a range of Beatles-related costumes while miming to the track. His attire in these scenes represents a chronology of periods in the Beatles' career--starting with the Hamburg-era black leathers, followed by 1963 mop-top wig and grey collarless suit, and soon changing to the iconic "Sgt. Pepper" uniform.