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. This tapping "has been incorrectly identified as a metronome in the past", according to engineer Geoff Emerick, who says it is actually the sound of Paul tapping his foot. McCartney also said the same in The Beatles' Anthology documentary. Emerick recalls as being mic'd up separately. Footage included in the bonus content on disc two of the 2009 remaster of the album shows McCartney tapping both his feet alternately while performing the song.
In any case, it's amazing to hear Paul's voice and guitar playing on one of the most beautiful songs in The Beatles' catalog.
[Via Steve Silberman]