I just stumbled across this:
It looks like a promotional video, or perhaps a clip taped out of the middle of some show, from the '70s (based on the automobiles) for the Shin Koiwa Rolling Stock Center. It shows sales people showing pictures of freight cars, and various stages of assembly and scrapping.
The video is low quality (some of the welding scenes are just pixel noise), but there are a lot of interesting visible details here.