I don't care about the legality of an NDA. The question here is why was the porn ho was made to testify....of course an NDA doesn't mean shit if one is compelled to testify (any well crafted NDA should even say this) or if it is cover up a crime.
Let's say I rape you in the butt and give you hepatitis, before God burns down my city of course, and to keep you from telling everyone about it I pay you off and make you sign an NDA. Of course you can then testify in court I ravaged your poop chute without your consent.
I didn't read the rest of your post, because I think the trial is dumb anyways.
What was the “crime” it covered up?