Does he explain away the correlation in Utah? It seemed a safe bet that Utah has the US's highest birth rate, given Mormonism there. A search confirmed it. (Sorry I'm lazy on video sources.)

No he doesn't mention it from what I recall. The data discussed is broader (and more longitudinal) than that trend.

Personally I'd guess the birth rate there is a direct result of the church's push for more children, but I don't really know.