Andy Black, Cliff "JohnnyBax" Josephy and a third player at the table got into an argument about the showing of hands and who was at fault during a certain hand.
After Josephy had won a pot against Black, he mucked his cards towards Black's direction. While the intent of the muck isn't known, Josephy did comment to Black that he could look if he wished. Black took the opportunity to lift the cards up for his view and discard them into the muck. The third player at the table, wanting to see the cards Josephy had agreed to share, took the two cards out of the muck and asked the dealer to reveal them for the whole table.
There are two rules at play in this situation. The first is that if you show one player at your table a hand, the entire table has the right to see it. Josephy did not violate this because he mucked his cards which were later legally retrieved by Black. The third player spent most of his time attacking Josephy even while Black was trying to take most of the blame. It didn't help, however, that Josephy was spending an equal amount of time arguing that the third player is not allowed to touch the muck pile, no matter the circumstances. This is also true.
In the end, the two players agreed to move past it and have been playing amicably ever since. It never hurts to have a brush up of the rules though, especially as we get deep into the series and people start studying every action by an opponent.