Bill Mollison is famous for his invention of the "permaculture" agricultural system. He's the inspiration for our back yard "food forest" garden.
I read through the transcript of the talk. Mollison seems to be discussing a form of "trompe" which takes advantage of geothermal energy as well as hydraulic energy of falling water. This is not a "limitless" process, nor is it likely to make petroleum obsolete, as the title of the video says. I can't find where Mollison makes any such breathless claims in his talk.
The Wikipedia article about compressed air energy storage says that it's competitive to lead acid batteries in terms of energy density and cost, but clearly inferior to lithium ion.