I saw that a few years back. One guy installed one and said that it does just was a subwoofer does... (moves air) But without the audible part of it.
You could feel it, but not hear it. He said that it wasn't worth it for the installation issues that a person would need to take into consideration (takes more than just a hole to blow the air through so to speak he was saying). He was sticking with his, at the time, $25 per pair, Bass Shakers. More accurate and even tactile distribution. By "accurate" I can only assume that he said that because of the lack of recorded "sound" that low, and that most if not all DVDs have bass audio set to what a normal (good) sub can handle, and not down that low.
Just repeating info I recalled reading a couple years back when I was looking at the thing.
