... and sometimes you can't change where they install if you wanted.
I've found that some of the multi-samples are installed at C:\Multisamples - or some place like that.
I don't remember if this pack is like that, but I had to copy some of the expansion packs to the 'correct' folder.
Mine are located here:
C:\Program Files\Cakewalk\Rapture\Multisamples\Digital Sound Factory Filmscore
You might need to use F5 to refresh the program listing after you move.