This is William H. Whyte‘s film ‘Social Life of Small Urban Spaces’ on the social dynamics of public squares and streets. At the time, it was considered as pioneering research because it used film cameras to study human conduct in measurable and objectiv way. The film was published with a book of the same title in 1980.
Whyte was also the founder of the Project for Public Spaces back in 1975. Today, PPS is a non-profit organisation that is using a Placemaking approach to advise on public space issues.