Thank You for your contribution and hints & tips, I really appreciate them!
Finally I was able to make them reply and although their site seems outdated and it was not the easiest task to get an answer about my issues they seem to be helpful and cooperative.
They retracted the DMCAs they sent to my hostings and now we are managing all possible issues via simple email communication.
I understand that scanning the web for a specific source of illegal content is tough, and trying to get in touch with the tubes and other sites is even tougher and very time consuming.. I understand why they send out tons of DMCAs instead of trying to just ask to remove the content. But it hurts.. :P
In 2025 one of the things on my list is to get our tubes whitelisted with all content partners we work with. I am not expecting that DMCAs will be gone, but it will probably be way easier for all.