What I think about the video "confession" is:
No, it wouldn't put Hank in the slammer for Drug Lording. It would be a big pain in the neck and probably put him through a really unpleasant and personally expensive legal process. (It would certainly cost him his job, but that's moot in that everyone knows once any of this gets out, Hank is toast at the DEA regardless.)
A large part of the investigation he would be subjected to would be focused on the money that paid his rehab bills. Even if most of the details of Walt's story are instantly disproved as fact, that's a matter that could still land Hank in prison, I would guess.
It's also Walt's insurance against Hank going after vigilante justice, since it begins with "If you're seeing this, I am probably dead, murdered by my brother-in-law, Hank Schrader."
It also sends a clear signal to the Schraders that all gloves are off, that even if this particular trick isn't the final solution to Walt's situation, there is no limit to how far he'll go in making their lives miserable if they, for instance, continue trying to snatch the kids.
So no, it isn't quite the fatal noose around Hank's neck that the writers probably want us to see it as, but Hank and Marie are right to be appalled by it.
Mike is right about that, as far as it goes, but I'm still wondering how he would have directed the conversation scenes in "Buried." What is exactly the right decibel level at which to discuss the mutual devastation of four deeply entwined lives?