Actually I’ve been using StreamFab Youtube downloader to download Youtube videos, not only youtube videos, but also videos of Vimeo, Facebook, etc. It works well.

I think a downloader will be neccessaire, it will cost too much money if we bought them all.

StreamFab is actually a great tool for you to download videos from streaming platforms, like Netflix, Youtube. You can take a look : https://dvdfab.fr/youtube-video-downloader.htm