El D-Box es, a lo bruto, una butaca a la que puedes conectar el BD, y que se "mueve" (vibra, retumba) de acuerdo con la información que envía esa función del disco.
Segun Wikipedia:
A standalone motion controller box or a PC based motion controller (requires a PC) reads information about a movie title directly from the disc or by using "motion code" provided from an active Internet connection and relays motion signals to connected motion-equipped seats. Currently the system supports a library of around 1,000 movies.