The prosecutor wasn't the one presenting it as evidence at the omnibus hearing. Frank was the one who raised the issue regarding April's statement captured by the footage, uploading the footage as evidence, and the judge rejected it as premature. Frank claimed he found case law that suggested otherwise and said he wanted to make sure "that it was raised as early as possible."
The order doesn't mention either of the recordings, but it also doesn't mention the issue of April's statement which was mentioned in Frank's motion and the omnibus hearing.
Put it this way: if the case proceeded to trial and then an appeal on this issue, would Nick's lawyer for that appeal be willing to concede that Frank didn't raise the issue and didn't present evidence regarding it at this hearing?