I seem to recall reading an article on a local military history magazine and part of the reason for the lack of such films might also be the vast amounts of destroyed film during the bombing of Dresden. Film canisters measuring dozens of kilometers of celluloid strips where kept in the basement of a church in Dresden, i think it was actually part of the luftwaffe archives.
During the bombing the church didn't receive a direct hit, but the use of incendiary bombs on the city for 2 days straight had created a lot of massive fires. Since celluloid is flammable, most of the films ignited due to the increase in the ambient air temperature destroying both the archives and the church in the process. I think the church has since been rebuilt as a memorial to the civilians who died in the raids.
Now i don't know what kind of footage they kept there, it could have been reels of guncam films and not instructional videos, but it would be nice to have access to them nevertheless. Especially since the Germans are always so crazy about documenting everything, it would be a museum in its own right if it had survived
