1. Open Facebook.com, find the video which you want to download.
2. You need Facebook video URL/Link, so there are two ways to get video URL:
i) Click on video then copy the URL from address bar as seen in screenshot below:
ii) Right-click on the video which you want to download:
iii) Now, copy that URL.
Now, open downvid.org, then paste the video URL in the box and click on "Download" button.
4. After that, you will be asked to select whether you want to download HD Video or SD video, choose whichever you want. That's it!