The Girl Chewing Gum is definitely worth a watch if you've got a spare 10 minutes. A short film from 1976 by John Smith, it shows people, cars and birds on a busy street in London all being directed by a narrator. Widely acknowledged as one of the most important avant-garde films of the 20th Century, it's also pretty funny and is a great slice of people watching featuring '70s haircuts, clothing and cars.