I don't think so, especially if Jill, as a former child victim of Josh, testifies. It is evidence of pedophilia, and a prior history of this. The fact that it happened prior to age 18, and he was not charged is not the issue.
He obviously has a propensity for this. Otherwise, he could have downloaded ten million videos of adult women, no one would have cared.
The fact that he prior engaged in pedophile behavior, and as an adult, continues to seek this type of material is disturbing. Especially as he has young girls in his home.
There is a problem there. That is why Jill's testimony is going to be crucial for the prosecution.