The objective of the Library of Economic Possibility is to make complex ideas digestible for people who aren't experts in economics. Deaton has played to that theme by visually mirroring that mission. The piece uses simple visual metaphors to represent the narration, subliminally reinforcing the message that the Library of Economic Possibility is a place for consumable content.
I think flat vector design is sometimes overdone, especially in explainer videos. However, Deaton's use of the flat style blended with some 3D shapes creates a sense of depth that is really nice.
I found some great examples of core animation principles.
Squash and Stretch
Watch how the balls fall and hit each other and then settle.
Follow Through/Overlapping Motion
Here, the "skeleton" of the object is the outer rim, while the "fat" of the object (or the parts that lag) are the inner dots, which drive the motion of the inner lines.
Here, the "skeleton" is the inner octagon, while the "fat" is outer octagon and subsequent added octagon lines.
Here is a good example of using the z-axis to give the illusion of three-dimensionality. The circular movement also makes it very clear what is important and what is secondary, supporting the narration.
Okay to be honest, I don't really understand appeal quite yet, but I think this shot is appealing.