There is a walking animation that applies when someone uses a joystick to move around, but otherwise generally all movement of the avatar is directly driven by the positional tracking of the user. (All VR users have the positions of their hands and head tracked, but some users also have trackers on their waist and feet too.)

There are also a couple people in the video that aren't using VR but are using VRChat in desktop mode. It's pretty obvious because their hands don't move from their sides while standing, their head motions are limited, their body never sways, etc.