I know I heard or read that, too, maybe in a German preview. I've already wondered why no one mentioned it here, as it'd be quite a huge thing after the instant-retry after losing in FFXIII/-2. I'd welcome it! Adds a satisfying weight and tension to the game. You really don't want to lose progress in the middle of a long dungeon. Losing an hour of precious game time after every lost battle in Lightning Returns really added a lot to it and made you pay attention to every single encounter because losing often meant having your whole time plan thrown off if you didn't have enough time left afterwards to finish a time-sensitive/locked quest you were in the middle of doing and had to waste a whole day again to wait to finish where you had left off.
I'll try find my source. Maybe I heard it in the same video you posted, though, can't remember.