This is a Navy department training film. According to the film, at the time is was made (1943) the only Navy aircraft approved for inverted spins was the N3N-3 (and the film does say say N3N-“Three”).
This video has been discussed in the N3N Pilot’s Lounge (the Yahoo Group) but I recently ran across it on YouTube. I have added it to the “Articles and Video” page on the menu at the top of the Blog.
A direct link to that page here: Articles and Video