This is an example of how off the rails the United States has gone.
The pharmaceutical industry that has handicapped countless children with mercury-based vaccines is able to buy a study that says a known neuro-toxin is good for the brains of infants and small children and improves their behavior!
First, "behavior" is not quantifiable and is completely subjective. There's no science here. Just corruption of science on an inconceivable scale.
Second, mercury is a poison, a neuro-toxin that destroys the functioning of the central nervous system. There is no conceivable justification for it to be mainlined into the bloodstream of anyone for any reason ever.
You may want to watch this twice so you can be sure you really heard what you thought you heard. You did.