All they need to implement ad block detection is user consent, which they likely cover on their terms of service and privacy policy.
For some reason your link doesn’t load. Is it this? https://iabeurope.eu/wp-content/uploads/2019/08/20160516-IABEU_Guidance_AdBlockerDetection.pdf
Because of GDPR, in the EU user consent has to be explicitly asked for and given, not implicitly via some catch all in a 20 pages Terms Of Service.
Hence all the cookie pop-ups.
That is addressed in the source I linked, which is an industry groups advice to publishers on the implementation of ad block detector. They specifically say that having it listed in your ToS is a defensible strategy but could have some risk. To mitigate the risk, you can introduce either a consent banner, consent wall, or both.
It’s an interesting read, and something I wish I’d had a few years ago in a prior role when I wrote my organizations gdpr strategy, though I’m not an expert on EU specific law.
“Defensible strategy” doesn’t mean much until it goes to court and gets tested - just look at all those Cookie Popups in the early days with “user must uncheck everything to Reject” anti-patterns which ended up being ruled as not valid per the GDPR which is why nowadays all the major websites have “Reject All” buttons in those.
So far on everything that had not yet been explicitly clarified, when it did the ball has consistently fallen on the side of explicit user consent on colleting any “user identifying” data beyond that which is technically required for operation and Ad Blocking is not a tecnical requirement for the operation of a video sharing website.
Indeed, it ultimatelly will need to be tested in court. My point is that relying on an expectation that a court will rule that the collection of user private information for remote processing related to a functionality which is not technically required without explicit user consent is ok if there’s some entry somewhere in the ToS, is quite the wild bet as that would be a massive loophole on the GDPR, and further, even if that that did happen, relying on Commission not rush to close such a massive loophole is also a wild bet.
