I missed this video time capsule when the Los Angeles City Clerk's archives put this on You Tube in October. It's a training film for traffic officers from 1946, and shows a number of downtown intersections. The metadata cites 9th and Hill streets, and I'm pretty sure I see a scene of pedestrians walking through Pershing Square before the surface was elevated for the parking structure beneath the park. Or maybe it's MacArthur Park? It's the screen grab I use above, so maybe someone will know.