Depending on your level of paranoia, one of these might work.

1. Buy a prepaid reloadable credit/debit card. In the US you can do this at major supermarkets, Walmart, and I think many convenience stores. You can load this by transferring funds from your normal bank account.

Your bank can tie your identity to that, but they don't know what you are using the prepaid card for. The prepaid card company knows what you are using it for but doesn't know who you are. Same with whoever you buy things from with it.

2. Buy a prepaid credit/debit card using cash.

3. Buy a prepaid reloadable credit/debit card using cash. Use this for your internet purchases. To reload it, buy prepaid non-reloadable debit cards using cash and use them to reload the reloadable card. (I'm not sure you can use one card to load another, though. Using credit cards to load prepaid cards is usually forbidden I believe, but I couldn't find anything on using debit cards to do so).

I'm in Europe. You cannot buy+use credit/debit cards without going through an identification process here.

You are watching YouTube. They have your IP, and can tie your identity using that.

Who? And how would they do that?

Unless you are very careful google knows exactly who you are even with multiple layers of ad blockers and VPN. It's built into their browsers and services. They are the best in the world at it barring state agents like FSB and CIA.