Ok, as I was intrigued, I did some searches so I perhaps could recreate the steps I took for the epub contents indexing. And encountered on MobileRead several false positives in the past by BetterRed... So I now understand your eagerness, BR, on my remarks
Unfortunately, I could not find my aha erlebnis from the past, when I positively did had something working. I did at least installed a separate PDF iFilter and possibly some others as well (ZIP, HTML, ?). So I figure that combination and perhaps some other tweaking (registry?) somehow made it work, but that's it.
I'm sorry, but due to my age my brain is not up to par anymore.