Goto your facebook account and pause on any Video or Play it and you will find 2 buttons below every Video and also find 2 buttons upper right corner on every video to Download in HD or SD Quality as MP4. See screenshot below:
Go to any single video and you will find 2 blue buttons upper right on every video and you can also download the videos on HD or SD Quality as MP4. See screenshot below:
Now, Click on "Download SD video" or "Download HD video" (if available) to start downloading the video.
Freefbdown is the best Free Online tool for Facebook Video Downloader.