That was a great video! Thanks for sharing it.

Worth pointing out:

1. While the video seems like a hidden gem, and I certainly didn't know it, it turns out that this version with worse resolution (240p vs. 480p) has 21 million views.
2. The same channel ("US Auto Industry") as the 21-million-view video above, shares this Vintage "How Cars Work" Films playlist which contains 10 other videos from 1936-1956. I haven't checked any of the other videos myself, so I don't know if they're as good or as timeless as the one on differential gears. But they're sorted by view count, and e.g. the second one on Spinning Levers still has 10 million views. (Caveat: With Youtube versions of old famous films, you can never be sure whether the version with the most views is the one with the best resolution. So if a video has an unwatchably low resolution, it sometimes pays off to search for versions with better resolution.)
3. And on the same channel, there's a bigger playlist called How Cars Work and Stuff Like that, containing 22 videos but with much overlap to the first playlist.

EDIT: And if someone really wanted to dig into the Jam Handy archives, a ton of their films are available on the Internet Archive. Realistically speaking, though, most of them probably aren't very good or relevant.