Copy Facebook Video Url: Right click on video -> Show video URL -> Copy Url
Paste Facebook Video Url and click Download
Download SD (normal quality) or HD (high quality) video.
Note 1: If the video opens up instead of downloading, then Right Click the button and "Save as...", "Download Linked File ...", ... to download the video.
Note 2: If you get an error, then check if the video is public
and not private .