Thanks for your reference to the video and your own DIY account. Very interesting. I watched a Townshend video and there are some more and less convincing elements to it. The vibration dampening is impressive. However, a couple of things stood out to me.
First, I don't usually walk around my room while listening, and no one else does, either. So that "solution" addresses a non-existent problem.
Second, while the earth's seismic activity is an interesting factor, isn't the person in their chair (and the air in the room) also vibrating, and at the same rate? In other words, if I was to dampen the earth's seismic vibration on my speakers -- but I am still not isolated in a similar way -- wouldn't I be more out of sync with my speakers as a result? It seems like an angels-dancing-on-the-head-of-a-pin issue, anyway.