Nope, I think he is referring to the actual screen casing. i.e. the long cigar shaped tube that holds the rolled up material and is fixed to the wall or ceiling.
I would say, if you are fixing in a dedicated theatre then most likely the black velvet covered one. If in a day-to-day room with coving, ceiling, etc in white then go for the white version. Generally determined by the environment in which it will be fitted.