Hope you're wrong about the "50-50" chance of a walkthrough tape. If there is such a tape, no one outside this board and other loyalists will believe that it was "unauthorized." There will be a former (if disgruntled) Pats employee with a tape made by a member of the Pats staff (himself or whoever he claims made it) of a Super Bowl walkthrough. That will be all that 95% of people outside of New England will have to hear. Since the organization has already acknowledged breaking other rules, the case will be closed in the court of public opinion. As a result, the pressure on Goodell to go along with that majority will be overwhelming, from Specter to sponsors to other owners to the media, so i think you're whistling past the graveyard there.
I join those who would like the Patriots to be more active and believe that the organization has dropped the ball since September by not having an aggressive, in-your-face, crisis response strategy that addressed every false claim head on as soon as it was raised not through press releases but by making members of the organization (and other supporters) available with talking points to directly refute the outrageous stuff that has been thrown around. The fact that the greatest effort in this regard had to be initiated by people on this board shames the Patriots' management and I don't know what the folks in Foxboro were thinking.
Beyond that, though, I don't see what legal recourse the patriots have (please read to the end of my comment before responding) if the object is some sort of law suit for material damages. I'm not sure how much they've given up in their indemnification of Mr. Walsh, since we don't know what he has. However, if they are going to sue somebody for monetary damages (and not just try to get Walsh in trouble for walking off with tapes and papers, which happens every day in the business world and which is rarely if ever prosecuted unless major damages can be shown), two things will be necessary: one, they need a target with deep pockets or at least a mammoth insurance policy; two, they need to be able to quantify the damages they have suffered--to date, the team has a 98% response on its season ticket sales at dramatically increased prices (with plenty of people ready to snap up the 2%), there is no impact on their TV revenues as they are contractual and I doubt that their Merchandise sales have taken much of a hit that couldn't be explained by a second consecutive Playoff exit in disappointing fashion.
So, what damages are they going to show if they want to sue the pants off of somebody (as much as I would like them to be able to do so)? If they argue that the value of the franchise has been impaired, they would need to put it up for bid and then show that the bids were lower than prior estimates of its value, such as are found in Forbes and among Investment Bankers.