Ah, great minds. @GeeGolly posted while I was writing this. I thought that Jon had signed an NDA for the show and a later one as part of the divorce settlement.
I really don't see JB going to the trouble and expense of getting his own NDA drawn up for Amy to sign. I'd bet a hot dinner that the only NDA she signed was in connection with her appearance on the show. In that case, I assume that the other party to the NDA, the one for whose benefit it exists, is TLC. Not JB. JB could sue to enforce an NDA signed between Amy and TLC, ONLY if JB were a third party beneficiary of the NDA. That's someone who's not a party to the NDA, but is within the scope of the NDA's intended protection.
Obviously we don't know what the TLC NDA says, but I'd be surprised if it says that JB is a third party beneficiary, and I doubt that JB would want to fund a lawsuit over the issue if he's not named as a third party beneficiary in the TLC NDA.
However, I can see JB doing some sword-rattling at Amy, and Amy deciding that she just doesn't need that bullshit in her life right now. As I think someone upthread has said, she's a new mom, and she and her husband have small businesses which have been slammed hard by the current pandemic. That's enough to be on anyone's plate. Without your skanky uncle stirring the shit over some YouTube video.
As to the interview with Amy that got taken down (or set to private, basically the same thing) - I watched a long video where Katie was talking the whole time. It wasn't a live interview with Amy, but rather Katie's recap of her exchange of messages/emails with Amy. Amy had answered questions. And, it was innocuous. I don't remember her talking about a retreat but I may have missed it. Amy made clear that she wouldn't be answering questions about her family, or dissing them. She said she loves her cousins. She specifically said she and Jill are close, that Jill has recently modeled some clothes for Amy's store - and was compensated for that. If that's the video that got taken down, it was innocuous to the point that I was sorry I'd wasted the time on it. Was that the one that got "someone's" shorts in a knot? Jeez. The term "snowflake" comes to mind.
@Scarlett45, that was a nice brief statement about NDAs. I believe they are enforceable more in the area of private business dealings, than as to subjects of public interest such as government operations, expenditure of public funds, etc. And of course as you said, you can't cover up crimes, fraud, etc., with an NDA. I probably watch too many true crime shows, but I've just tickled myself by imagining some loony narcissist lawyer or accountant deciding to off someone and having his henchmen sign an NDA. And you KNOW there's someone out there who is evil and nuts enough to try something like that.