Assuming for the sake of argument Belichick ordered a pervasive cheating endeavor, do you honestly believe, with all the compartmentalized security (people in the Pats organization know their jobs but not the jobs of other people or groups in the organization) he would actually leave this Kaiser Sose character in a position to expose the illegal endeavor? Only if they are complete morons. Belichick may be arrogant (believe what you want about the videotaping violation-he liked doing things his way and thought the rule was stupid-he was obvious, not sneaky, in his videotaping), but he is not stupid.
The court of public opinion will never believe Belichick, not if he hooks himself to a polygraph, not if he says he has nothing to confess before being burned at the stake. Could a garden variety idiot like Walsh, a low level, video media guy who would be aware of the Rams practice schedule by virtue of media bulletins, unilaterally tape that practice in an effort to enhance his position with the organization? Uh, yeah. Don't forget the fact that the Pats played the Rams well (24-17) during the season, so where is the motivation to engage in something Belichik clearly could get caught and embarrassed doing? This ploy is not the sidelines stuff, it is the stuff that kills a team's desire to win and creates scandal right before the Superbowl. It tells a team the coach believes the team is outmatched and cannot honestly win the game. That would be stupid.
Walsh has nothing. If the Pats thought he had videos, he would likely be sued long ago for theft of team property and violation of his employment agreement. If Walsh was able to sneak these smoking gun videos out, there would be no chain of custody implicating him and he would have leaked them to the media for a big payday (and given the love of the mediots for the Pats, somebody would have paid that tab). Something about Walsh does not scream love of the NFL and its competitive balance. This guy is therefore the NFL's equivalent of Geraldo Rivera's Al Capone vault episode - a huge amount of wasted attention that will result in absolutely nothing but lost time.