This could indeed give problems, but for testing this instance it would white list what i needed, so the test is still valid.
It blocked all calls to any of the "fingerprinted" domains and let the 2 aforementioned domains trough, still no video. This means that youtube does not only send it's adds via those domains, but also the content. So blacklisting it, with a wildcard or otherwise, is not our solution to blocking these adds.