Today, on Twitter, a follower asked us about a way to save (a) video(s), so we answered as follows:
This is an article which we put together tweets above and translated to English.
How to dowload (a) video(s) from YouTube and save them on your machine.
After installing the "Download YouTube Videos as MP4", on a video page on YouTube, your FireFox displays a "Download" button at the left of "+Add" button. And after clicking the "Download" button, your FireFox displays "MP4 ***p(**MB)" at the bottom of the "Download" button. So, click the "MP4 ***p(**MB)", you can dowlonad the video to your machine.