@aaden
The main message of his video is generally against pre-ordering, yes, but part of his arguments are about ingame goodies in particular. More precisely, he says (among other things) that in order to encourage pre-ordering, game developers want to "tempt" you with exclusive ingame goodies. Around 10:30 he talks about how pre-ordering encourages "horrible development practices" where you split the game content and split development resources, so that a normal purchaser won't enjoy the full experience.
It's one of his many arguments against pre-ordering (others being bad review inclinations and, well, maybe actually buying a game that sucks), but it still stands on its own.
Edit: he himself says that if they find a way to improve the game for pre-orders, without splitting development resources (e.g. directing the art team, after they've finished their work and are done with the game, to create new models), then that's fine. But if they initially split the team to create completely unavailable content for those who pre-order (e.g. being able to go to completely new areas), well, that's problematic for the industry.