CONFUSING!!! AND DOESN'T WORK! "Social Video Downloader" is how it appears in the Facebook browser tab list of extensions. Extension didn't work -- on the facebook tab, the extension was grayed out and couldn't even be invoked. When you click on the gear icon there to manage the extension, you go to the tab to manage "Social Video Downloader."

The developer link is there: getfvid.com

Clicking on that link takes you to the developer's Mozilla add-on page which lists ONLY a new extension titled, "Video Downloader for Facebook by getfvid.com"

The screenshot showing how to use the extension shows a GREEN BUTTON in the upper left corner of the Facebook tab. The green button does not appear for me. Running Win7(64) with Firefox 115.18.0esr (64-bit).