By far the easiest option is to use a public instance of invidious.
Youtube links looks like this: https://www.youtube.com/watch?v=AaA1a1AaA-a
Invidious links look like this: https://www.invidio.us/watch?v=AaA1a1AaA-a
Links can be manually changed or converted with an add-on.
Open a terminal.
Install youtube-dl on a Debian based system.
sudo apt install -y youtube-dl
Download a video with a command like this:
You can get an RSS feed of a channel if you have its ID like so:
For example, here is the feed for Kero Kero Bonito's youtube channel:
You can find a channel's id either in its URL or by inspecting the source and searching for "channelid"