Honestly haven’t had that issue at all yet. If that happens, this userscript can be a solution (with something like grease monkey) https://greasyfork.org/en/scripts/477725-youtube-iframe-adblocker. Using NoScript to turn off JS should also work. As a last resort you can use a script that redirects YouTube videos to invidious or some other alternative.
They can. Though it’s just easier to use librewolf in my opinion. There’s a project called arkenfox which makes this easier to config settings manually for Firefox. Take a look into it.
The only annoying thing libre doesn’t turn off automatically is WeRTC which can be turned off in the flags with media.peerconnection.enabled set to false.
The solution is to use Firefox or even better librewolf with uBlock. If you already have these, purge the filters cache and then update it back again. If you still have problems with this after doing these steps, there's probably some extension conflicting with it or an extra manual filter you added. Cheers
One of the biggest tinfoil hat youtubers out there, heh. I think he has some good stuff though, other stuff is just plain speculation and paranoia. Email in general is not secure, not everyone can self host or wants to self host. Proton does it's job for anyone that needs an alternative to Google and also wants to maintain a set of features like calendar, tasks and so on.
Regarding music, there’s also the slavart discord and their bot which allows you to download music from different streaming services in lossless formats