The first link seems to be broken, but the second one works.
It's very interesting indeed, very pedagogical in a German kind of way
At the end of the film (and of the assembly line), Bf 108 D-ICRO is rolled out, as well as several with Wehrmacht codes : WL-IQJW, for instance. This should help date the film quite precisely, but I would guess between 1936 and 1938.