Follow through and overlapping action
Follow Through is when the main elements of a movement will stop while others continue due to the momentum of that movement. In most cases the movement of a figure will have parts that will start and stop at different times. In this image below, the head of the dog has stopped moving but the ears and jowls continue in the same line. It means that the animated sequence has a less abrupt end, making the whole movement more naturalistic.
Overlapping action is closely linked to this as it involves different parts moving at different rates. It means that there should always be movement within a sequence so that the figure continues to be realistic. It refers to the secondary movement of parts, like the movement of a hand when the arm swings.
In this clip, the overlapping action is within the tail and the ears. It allows for continuous movement within actions to emphasize the bouncing characteristics.