He just said it's never before happened before that the home team has won all 8 games in the WC and Division round, so the odds are (paraphrasing) either the Texans or Giants will win.

This is a case where the statement is might be true, but for completely the wrong reasons. If the Packers and Ravens each had a 70% chance to win, the chance of both winning would be 49%, but it doesn't have anything to do with the results of the other 6 games.

BTW, I have not seen any book offering this wager, but if you do want to bet that either or both of the Texans or Giants will win, the odds implied by the individual games, say that's about a 44% chance.