I have seen that you can use VLC player to play online videos locally on your PC.
The problem with that, is that it is a function of VLC, so it is player dependent, and it doesn't work on every website.
So my question is if there is a program or a command-line utility (like livestreamer but for videos) for Ubuntu that works on every website and on every player (VLC or mpv etc.). I know that it is probably a longshot but I would like to know.