You know you're in for 10 minutes of awkwardness when the robotic narrator says in sleepy monotone, "People are attracted to cartoons because they love to laugh." Moments later, the narrator tells us that circles are the key to cartooning. It's just circles all the way down, folks.
When I was a kid, I used a series of "How to Draw" books that promised I'd be able to draw all kinds of amazing things, typically starting with a few circles. I didn't put in much effort (let's be honest) and I never became an amazing artist either. In this 1956 film, we get the film version of those books, minus any verve whatsoever. There is virtually no music, and long stretches of awkward silence accompany footage of an unnamed cartoonist sketching stuff. There is also a serious obsession with "circles," but I would argue that they mean "arcs" and "ovals" in many cases.
The most interesting (and useful) part of this video comes just after the four-minute mark, when we see how cartoonists can sketch facial expressions by examining their own faces in a mirror. By watching small movements of the eyes, eyebrows, and mouth, you can communicate a lot!
If you're ready for a nap—ahem, I mean a vintage lesson on cartooning!— just turn this on.