There is no need to try and imagine what is witnessing all of this; it’s enough to know and to confirm that it is witnessed. That witnessing place is your Absolute space.
This exercise is a physical and practical metaphor for the functioning of the universe, for the ground of Being — which is Unmoving — and for the witnessing of both of them. This is not a pranayama exercise, but simply is a kind of window in which your are able to see the functioning around your Inmost Being, and what it is that is inmost, but cannot be seen.
The buzz is the waking state and its activities, witnessing of the buzz is taking place without any effort; it is coming from the ground of the being itself. The sense of presence is there, but even the sense of presence is also witnessed.
By the time you try and analyse any movement, it’s already gone. So the best is when you come to the state of that inner emptiness where your actions become spontaneous. When you don’t think about that but simply observe that, you will feel very happy that there is a harmony unfolding in life that is not sourced from your mind. It is simply the harmony of existence.