This video footage is made up of excerpts taken from a Japanese war-time film. The film has a patriotic agenda and is titled ‘Ichiban Utsukushiku’ (The Most Beautiful). Directed & written by Akira Kurosawa (regarded as one of the most important and influential filmmakers in the history of cinema), the footage shows what an early Nippon Kogaku (NIKKO/Nikkor/Nikon) optics factory and the working conditions looked like in the 1940s.
The workers appear to be making trench-binoculars, similar to these ones. The film was shot between January and March 1944, largely at the Nippon Kogaku, Totsuka factory, Yokohama City. The factory was completely destroyed by fire as a result of US bombing raids on Feb. 25, 1945.
Thanks Ron Volmershausen!