You can still download age-gated videos with youtube-dl.YouTube videos I could previously watch, such as Rammstein's Sonne with two hundred million views suddenly needs an age verification. The other thing is that the age verification in recent years now requires giving your credit card details! So no, I didn't, and in the past I have definitely watched a thing or two through my YouTube account which needed an age verification but never a credit card number, until recently.
If you haven't disabled fingerprinting in your browser you will still be tracked, no matter weather there are cookies or not.Normally firefox deletes all cookies on exit, but I happened to be logged into a google account and suddenly an online clothing store is asking me if I want to visit the page of my home country or the country where I currently am. For a moment I wondered how it possibly knew then realised I had written google reviews for some things in my home country.