The mistake made in the video was the claim that an important meta-analysis of 27 IQ studies carried out by a team from Harvard University (Choi et al., 2012) - comparing the IQ between children from villages with high fluoride exposure and villages with low-exposure- reported an average loss of 0.45 of an IQ point. In reality, the Harvard researchers reported a loss of 0.45 of one standard deviation, which amounted to a loss of 7 IQ points. A huge difference. A loss of half an IQ point might be insignificant, but a loss of 7 IQ points would be very serious at the population level. Such a loss would more than halve the number of very bright children (IQ greater than 130) and increase by at least 50% the number of mentally handicapped (IQ less than 70).
Under any other circumstances this would be a very embarrassing mistake but on the matter of fluoridation the NYT is not embarrassed easily. For example, in 2015 the senior science editor wrote an email in connection with fluoridation:
“… I understand that you disagree, but I think it’s fair to say
that most members of the science staff of The New York Times
consider this debate to have been decided – in fluoride’s favor –
about 50 years ago.”