Bob, the way that this works is not one speaker shooting stereo. The top and bottom speakers are doing Mid/Side type projection, rather than Mid/Side recording like you do with a figure 8 mic and a cardioid mic.

The bottom speaker, because both sides are exposed, radiates sound like a figure 8 mic records sound. When coupling this with the front projection of the common mono signal that is common, it creates the L & R signals out in the listening space. If you switch off one of the speakers, you'll hear the stereo effect fold down to mono.

It's a brilliant idea, actually. Send me a PM to let me know how much you paid.

-Scott