Kitchen Stories is a fun film about a market study conducted in Norway in the 40s.
Swedish efficiency researchers come to Norway for a study of Norwegian men, to optimize their use of their kitchen. Folke Nilsson (Tomas Norström) is assigned to study the habits of Isak Bjørvik (Joachim Calmeyer). By the rules of the research institute, Folke has to sit on an umpire’s chair in Isak’s kitchen and observe him from there, but never talk to him. Isak stops using his kitchen and observes Folke through a hole in the ceiling instead. However, the two lonely men slowly overcome the initial post-war Norwegian-Swede distrust and become friends. (Wikipedia)
It may also be seen as a traditional way of doing qualitative research and more specifically, non-participant observation. Such methodology would likely be replaced by video camera recording nowadays, I think.