On your Facebook feed or timeline 'Right Click' on any video then 'Copy Video URL at current time'. See screenshot below.
Go to facebookvideodownloader.net. Then paste the URL and Click 'Download', like the screenshot below
Click on "Right click on MP4 SD" or "MP4 HD" (if available) and click "Save Link As".
Open the Facebook app and Tap Share on any video on your feed or timeline, then Tap Copy Link.
Open Firefox and Go to facebookvideodownloader.net, and Paste the Video Link before tapping Download.
Tap and Hold on any video format available (MP4 SD or MP4 HD).
Then Tap Download Link and confirm the download.