Does not work at all. Click on SC icon and get "Thank-you for installing this extension!...." - that's all it does. I am on a page loaded with direct links to pdf files and have refreshed (Ctrl-F5) but the add-on seems to do nothing. In the info for the add-on it mentions the "document search results or document list pages" - how do you get to these pages? There is nothing accessible via the FF add-ons page in my browser.
Try "Download Star"by Mark - worked first time for me for downloading over 100 pdf files from an educational website. Quick. Simple.