The Winter Soldier conference Kerry alluded to in his broad brush accusation of war crimes by US soldiers in Vietnam has been shown to be largely a hoax by people who were neither in Vietnam or not in the positions that they claimed. Also, "free fire zones" are not in and of themselves war crimes -- they just mean that the soldiers can shoot at enemy combatants without authorization, not that they can shoot indiscriminately.
I disagree, although we at FR have heard that so many times that many take it as established fact.
I believe that the expose you describe will take place in the future, if interest in this topic survives the election.
FR's own "Interesting Times" may have provided the central meeting place for WSI debunkers at wintersoldier.com: http://ice.he.net/~freepnet/kerry/