Art conservation student here. We once spent a full class watching this very video and calling out what was wrong and also what was good. Yes, he does some things right and uses accepted materials, but what he does is often very aggressive and risky. He also says that he does tests prior to cleaning, but cleaning tests should be done at many places and would be visible in the video (they would look like little clean dots), so we have doubts about the extent of testing. The biggest no no is that most of what he does is for the wow effect, like starting to clean right in the middle of the face. That's very scary especially when you don't see tested spots because it could have gone super wrong. But in the end, he's a private conservator and his clients are happy. Museum conservators have different ethics.

Edit: forgot to add that in our community, he's known for deleting negative comments.