My comment was intended to help educate the younger red-dot and expensive scope crowd who don't know how good irons can be. No offense intended.
That said, an M1 Carbine is neither of the above, and even though the stock GI irons are graduated out to 300, I would wager that the vast majority of people who've ever tried one at that distance would be impressed with the results of the video in question...which actually kind of reinforces your point about irons being adequate when somebody knows what they're doing, and in this case, he certainly does. Your analogy to an AK is not a bad one considering the inherent accuracy of the two designs (I might even give the M1 an edge), but it's also probably worth considering that with a 100 yard zero, at 300 yards, the drop of a .30 Carbine round (~48") is almost exactly double that of a 7.62x39 (~24").