Ah, if you’re interested in the HOW of Dzogchen “Meditation” here’s Alan Wallace giving a very brief Overview of Meditation in General and then proceeding to elucidate as to how such non-dual Meditation (it’s probably better called non-Meditation) as Dzogchen differs from the more well-known forms of Meditation such as Shamata / Vipassana etc …
Ah, with regards to what is referred to in the video as the “Baseline” or the “Ground of Awareness” here’s what Namkhai Norbu has to say about our Empty Nature :
From “The Crystal and the Way of Light” (pages 98-99) :