Nah, I think GP is spot on. I took a quick look at some of the materials and I would say that they're pretty outdated as far as current understanding of the game goes. It's more in line with how people talked about & thought about the game in the boom era (the 00s) or possibly even earlier, to be honest.

If I were teaching poker in a university setting I would generally work with a bunch of toy games to teach concepts of polarization, MDF, indifference, and so on. Those are the fundamentals of poker theory in the modern environment.

I'll give you a concrete example. In lecture five at 15m he starts talking about donk betting, which is when you lead out with a bet on a street into the aggressor from the previous street instead of checking to them to let them bet (for example, you're the big blind, you call a raise from the button preflop, and then when the flop comes you bet directly yourself instead of checking). He mentions that this is unusual, which is true, because normally you would just check and let the person with the betting lead bet into you if you have a good hand, and so the donk bet is typically weak--but then he goes on to say that advanced players may exploit this perception by donk betting with a strong hand knowing you will interpret it as weak, and then you can exploit that line of thinking, etc.

A more modern view of donk betting is this: the "betting lead" is not anything inherent to the game but just an artifact of the range of hands each person has. Typically when you call preflop from the big blind, you'll have a wider range of hands than the person raising preflop, because they can't raise too wide profitably due to players left to act after them, and you get to both close the action & also get better pot odds on your call from the big blind. Not only do you have a wider range of hands, then, but you also lack the strongest hands (AA, KK etc) because you would have reraised (3bet) them preflop. So overall, on most flops, the preflop raiser will have a stronger range of hands and can thus be expected to "take the lead" betting.

But! There are some flops that can neutralize or even reverse this range advantage. The flop 654 rainbow is now better for the big blind than for an early position (EP) raiser, because the big blind will have many straights, sets, two pairs, and pair+draw hands in their range, while the EP player will generally not have these hands. The EP's big pairs (AA, KK etc) are less strong, and some of their other strong hands preflop like AK or AQs have totally whiffed too.

As a consequence, it is correct for the big blind to have a donk betting strategy in this situation--the way the two ranges interact, the big blind is now incentivized to put money into the pot directly, and in fact, if the big blind does not have a donk betting strategy on this flop, the EP player should respond by virtually never betting themselves. The big blind is incentivized to bet frequently with a small sizing and put pressure on EP's overcards; if you have, say, 86s, and you can get a hand like QJo to fold, that's a pretty decent result on the flop, because QJo has six outs to improve to a better pair.

Anyway, sorry that this example was probably hard to follow if you don't play poker, but it's probably illustrative of some of the ways in which poker theory has evolved over the years--more focus on the specifics of range vs range interactions. There are many more complicated and intricate examples on turns and rivers that solvers are very good at finding but may or may not be obvious to humans.

source: semi-professional online cash game player