Everything I have ever read clearly states MMCD was not even on the drawing boards till the early 1990's. I find it highly unlikely a MMCD prototype was at the 1988 CES show. It wasn't even finalized till 95.
I attended the Stereophile convention in 1996. Sony did a demonstration of a protype MMCD disc and player: they played a sequence from Speed and showed us where the layer-switch occurred during playback of the clip, and they switched from 4x3 downconversion to 16x9 on the fly to demonstrate how the encoding process was geared towards new 16x9 displays.