That commentator is a doofus. I don't see a problem with Chad checking the river here. Chad says it himself, if she didn't have an ace then she probably wouldn't have called. Chad made the most he possibly could have from that pot. If he bet then at worse it would have been a split pot. Especially the way the hand was played Chad was going to extract no more chips from Chrissie. Chad may have made a mistake on the flop unless he felt he was trapping, but a bet on the flop would have been reraised and he would have ended up losing the pot. Swings and roundabouts i suppose