Watch: Paul McCartney and George Martin in studio recording "Blackbird" (1968)

One minute and 33 seconds is just not enough, especially if the cinematographer decides to focus on Paul's shoes for an inordinately long amount of time. However, the shoes were an important part of the song. From Wikipedia:

Only three sounds were recorded: McCartney's voice, his Martin D-28 acoustic guitar, and a tapping that keeps time on the left channel.

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