That's the path to a regular FF profile. The script only works on the special bookmarks.html file. Maybe you haven't done this:
- type "about:config" in firefox inputbar
- type "browser.bookmarks.autoExportHTML"
- set it to "true"
- close firefox
After that the bookmarks.html file should be generated, and updated, on each firefox restart. And then the FFBookmarkUnpacker should work.