Open Facebook app on your phone/or go to facebook.com Web on your browser.
Choose whatever video or photo you want to download.
Click to the Share button at the right bottom.
Click to the Copy Link button.
Download by using your browsers: I want to keep things simple for you. No need to download or install any software. I make an application for this purpose as well but you can only install whenever you like.
Go back to fbdownloader.online and paste your download link to the field above then click to the Download button.
Wait for our server to do its job and then, save the video to your device.