When moving around, the character's legs and arms rotate as if the player is walking, and this is the only version to do so. It is led to be believed that it is a bug, because of the unnatural way that the game deals with it.
When attempting to walk , the arms and legs stop as they should, but when finished walking, the player continues to not have the unnatural movement until afterward. It would be assumed this is so the animation could finish, but it is obvious visually that the animation is long finished before the arms and legs unnaturally begin rotating again.
TL;DR: The arms and legs move unnaturally when looking around, this is an issue with mobs as well. If this is not a bug and instead a feature, my apologies!