DOES NOT WORK. PERIOD. I downloaded this a couple of weeks after the Firefox Quantum update. I'd previously used Flashgot because it caught all media files and handed them off to my download programs. Flashgot also worked on all my platforms (Windows, MacOS, Linux) which was why I loved it so much. I got Bulk Media Downloader because Firefox recommended it as a replacement. After getting it, I tested it on various sites (YouTube, Vimeo, Twitter, etc) and it FAILED ON EVERYTHING. I went over the instructions to see if I missed anything. I also restarted Firefox without any add-ons and returned it to its default settings: STILL DIDN'T WORK. I tested it on Windows or Linux (to see if the problem was just on my mac) but NEITHER OS VERSION WORKED.