It's for recording animation, for characters and other things. So you could possess a character head, hands and if you have additonal trackers also feet or other body parts and record that.
There is some documentation here (note there are also subpages in that wiki)
Scene Animation Scene Animation refers specifically to animations on Person Atom Controls or Atom Controls captured within your scene or driven by the scene animation timeline. This is separate from the Built-In animations available on the Person Atom, any script driven animations like...
hub.virtamate.com
Besides the VaM build-in system there is also the Timeline plugin (by AcidBubbles), which is better because it can also animate things like morphs and is generally just a lot better.