To download a video from Facebook, you can follow these steps:
Find the video you want to download on Facebook.
Right-click on the video and select "Show video URL."
Copy the URL that appears in the pop-up box.
Open a new tab in your web browser and go to a Facebook video downloader website, such as fbdown.net, savefrom.net, or getfvid.com.
Paste the URL you copied in step 3 into the input box on the downloader website.
Click on the download button or the video quality you prefer.
The downloader will generate a download link for you to click and save the video to your device.
Note: It's important to respect intellectual property rights and only download videos that you have permission to use or that are in the public domain.