In her article, "Genealogy on Film: Industry on Parade," Judy Rosella Edwards explores a fascinating resource from the 1950s, a collection of films showcasing the industry of America and Americans. As the article points out, the workers in the film were actual workers on the job -- not actors: hence, simpler times. In today's promotional films (including folksy commercials), you can pretty well bet actors are playing the roles. The genealogical value of the Industry on Parade film, given its scope, is pretty amazing, and certainly worth checking out the titles to see if any of the films fit the time and place of your ancestors.
More and more we are seeing film being made available as a genealogical resource. The WWII ‘United News’ Newsreels, being one example. Edward's article brings to our attention yet another area to explore -- documentaries and other films featuring real people, mostly without "staging." It may take some sleuthing to find out what's available and where, but then, that's what we do.