Unclear from the article, but what audio sources are they using? Is there a meaningful 5hz signal in my Blu-ray soundtrack?

Even C0 (for instance on a Bosendorfer Imperial) doesn't nearly go that low. You'd have to synthesize the sound, I don't think any normal arrangement would pick it up even if it was present in a performance (for instance, that organ mentioned elsewhere in the thread). 70 mm Dolby Stereo tracks from motion picture reels will go as low as 3Hz. I'm not sure if that makes it to Blue-ray though, would be nice to try for a lark but not enough of a win to shell out money for.

Low frequencies can occur in nature, waterfalls, earthquakes and the like. Here is a writeup, with photos, of a multiple rotary subwoofer installation for the Niagra Falls Fury show about the creation of Niagara falls.

http://www.rotarywoofer.com/niagara%20fury%20index.html

I just had one of those 'why didn't I think of that' moments. That's really neat, thank you very much for posting it.