I'm confused.
He is getting the standard first time offender offer. It's not even really a deal, it is just the standard thing. It was reported in all the articles three weeks ago when he was arrested. As far as video, wasn't it the cops who videoed him after they got a warrant to bug the place? How can he sue them for that?
He did get the standard first time offender offer, not a "deal." Negotiations will occur but they will not result in that "deal" because it is not any kind of deal.
As to your second question, governmental immunity defenses would be a huge roadblock to any such lawsuit. Here, such a lawsuit usually gets dealt with by dispositive motions to strike or motions for summary judgment.
I do think Kraft may have some issues down the road, and whether that video comes into evidence or not is not the end of the case. The biggest issue in my mind is that at some point, file sealed or not, win or lose in court, that tape is gonna get leaked. Someone made a copy of it knowing its value and knowing TMZ will put in a great bid. For some $10 an hour clerical employee at the local PD, getting fired may be a voluntary, economic decision if TMZ offers enough money. So the media reports suggesting that Kraft has an interest in accepting that "deal" to get the tape sealed are overlooking the likelihood that copies have already been made for illicit sale at some later date.
The chances of viewing Kraft's cock being jerked or sucked (if anyone here is actually interested in such a viewing) is in my mind going to be possible or even likely regardless of what happens in this case. Apart from TMZ which simply has an interest in profiting from the usual sensationalism, there are Kraft's enemies, of which there are a few, and then there are the would be or wannabe owners of the New England Patriots, whomever they may be, whose motive would be to get him banned from the NFL if the criminal justice system and woman's rights groups do not succeed. The latter is already seeking a ban. Dislclosure of the tape would possibly lead to a forced sale - a la Donald Sterling sale of the LA Clippers after a tape got released exposing him as a racist dude, which was fatal to his professional sports involvement. He was a suck ass owner anyway and nobody has missed him. But it could happen to Kraft, especially if the tape gets released.
So the owner of such copy of such tape can basically auction it to all of the above. High bidder wins just like with Michael Jackson's medical records that got released (and Michael Schumacher's medical records after his skiing accident). This is the reality of what is out there and especially when the public has all been made aware of the value of the tape.