Does it matter? Most DVDs these days do contain trailers and lame previews. Heck, there were some issues concerning the compression of the 2005 version of King Kong on the DVD, and they still managed to cram a Volkswagen commercial and some NYC tourism thing onto the disc.

I'd get concerned if we find out they're being put on a single layered disc. Then the extra content will seem ludicris. If they do go with dual layered, then little things like a game demo and some commercials isn't really a problem as there should be enough space.