Classic animated series like Tom & Jerry are often studied by animation students so they have a better understanding about timing, staging, and character animation.
The short in this particular study is Down Beat Bear from MGM, 1956, which is heavy on the musical numbers and just the thing to show off your sense of timing as an animator, and the cutesy characters on the anime side are from a video game series called Touhou Project.
This surreal side-by-side short was created by YouTube user dfj688 using an animation program called MikuMikuDance, which explains all the dancing but very little else about this strange project.
-Via Cartoon Brew
That odd black disk was a sorta-kinda compact disk, except that it had grooves cut into it to hold an analog representation of the music.
That huge box that they threw into the tree? It was a radio! Yes, radios used to be thaaat biiig!