Always interesting to see the process. These behind-the-scenes movies from the Disney Studio in the late 1930's /early 1940's show the traditional animation process. Some of the process has been simplified or glossed over because these "documentaries" were produced for a mass audience , but there is still good information to be gained from these films and it's fascinating to see some famous animators like Fred Moore and Norm Ferguson at their animation desks.
Here's another one: "How Walt Disney Cartoons are Made (Burbank version)" made around the time of Snow White's release for the theater distributors who worked for RKO Pictures (the company that distributed Disney's films in the late 1930's /early 40's) . This footage shows both the late 30's Hyperion Blvd. studio as well as the "new" Disney studio in Burbank from the early 1940's -
A better quality version of this footage (without sound) is available here:
In particular the footage of Fred Moore working at his animation desk starts around the 1:55 mark in the above link (not embeddable, so you'll have to click through the link to see the footage) .
Some of this footage has been re-used in different "behind-the-scenes" documentaries about Disney.
A version of this was released to theaters for general audiences , titled "How Walt Disney Cartoons are Made" . Some , but not all of the footage is identical:
And here's a similar sort of newsreel report going behind-the-scenes at the Fleischer Studio in Miami, Florida, about 1939 -