I use Cookie AutoDelete (I use only Firefox, but that is irrelevant in this context.) Deleting all cookies (one could also use white^Hallow lists) works 98% fine. The problem is local storage. Pages can store the same (and more) information as in cookies in local storage. There is no add-on API to manipulate local storage. At the moment only an estimated 2% of all web sites use local storage to store tracking information. But if cookies get widely ignored/deleted, I am sure that will change.
I share your concern, but CAD has claimed to be able to wipe localStorage, IndexedDB and Service Workers for some time (a few months?). Check the settings screen of CAD and see for yourself.
That's what's doing it: you'll effectively get to Youtube without a cookie and be harassed.
It's a strange thing. It's so annoying that I've essentially given up Youtube. I don't care enough about the videos that I want to Login and whitelist (and have a profile recorded) the site, and this makes the experience bad. Ergo YT is fading from my life. Can't say that I miss it all that much after a few days, it has been a habit more so than something I actively enjoy.
Okay, I thought "without cookies" was referring to having cookies disabled.
I use Cookie AutoDelete and YouTube doesn't give me any problems for discarding its cookies. But maybe one of the uBlock Origin annoyance filter lists I use is taking care of the nag screen.
I’m making a dedicated Google account/browser profile for YT this week as I prepare to delete my main, ten+ year old Google account. It’s the last/only thing I actually need Google cookies for (outside of work/gsuite which is a different machine entirely).
Firefox: https://addons.mozilla.org/en-US/firefox/addon/cookie-autode... Chrome: https://chrome.google.com/webstore/detail/cookie-autodelete/...