Oh hey, YouTube has a mechanism for that! Simply down-vote the video, and any future viewers will know that the video is likely ineffective because of the visible down-vote count that Google didn't remove to make more money from advertisements. They didn't remove it because they value the health of people suffering from cancer more than money. Good on them.
While that would be great, in reality because of YouTube’s recommendations, the ones most likely to watch this crap are the ones already drinking the kool-aid and thus upvoting.
How time passes. This was not the case when down-votes were there. It used to be easy to identify when videos were full of shit, even with lots of views.
This might help others. It's crowd-sourced and uses averages, but for what it "feels" like, it seems pretty accurate:
People who believe in dumb idiot BS treatments tend to watch and like those kinds of videos too. Downvoting those videos might not be very effective because of the number of true believers watching them.