A lot of this feels like an attempt to deflect that people did play that way and that culture of play is worthy of discussion. Sure. It represents a subsection of play, but that subsection of play is the beating heart of OSR culture. How any given group played at any particular time isn't really the worthwhile question here. OSR play is not about playing games using techniques laid out in texts like Moldvay B/X to somehow capture the spirit of old, but because there's like a really fun game in playing to that text as directed. How anyone played in the 80s is immaterial to that.
OK, but the premise RIGHT AT THE START, like 0:00 of the video is that there's some 'unknown rule' that "explains the old school style of play." It isn't posited like "there's this particular rule in D&D that you can abide by which does X" instead it is posited as some sort of rosetta stone to explain it. The first issue is, as one of my posts in this thread already explains, his interpretation of the 'rule' (Volume 3, Page 35) is inaccurate and overgeneralized, let alone likely to have even worked, let alone be rigorously adhered to, in actual practice. Yes, if your character is COMPLETELY IDLE, Gary is suggesting that time flow for that PC as it would in the real world. Now, D&D doesn't say too much else about time, but AD&D speaks about tracking it systematically and precisely. So in that game (which many people don't call old school at all) yes, there might be an implication as to which PCs are present at a certain place and time (say to form a party).
I don't see how that is very significant, and I would bet my life's savings that such a rule was fundamentally retrospective. That is if your PC went to his house at the end of last session, so this rule might apply, then assuming you DIDN'T at today's session state that you rejoined the other PCs (who, say, adventured on Tuesday and thus are just now arriving at the town gate) then sure, "a week passes for him" (and presumably you've elected to play some other character). Should the player choose to state that the character got up on Tuesday and met the other PCs at the gate, well, then he obviously didn't sit at home! LOL. I mean, I can't literally tell you this is how Gary and Co played at any given point in time, but I can tell you that, from a 1975 D&Der's perspective, that would be how it pretty much always played out.
The video then, at around 3:00 starts telling us HOW PEOPLE PLAYED in the 1970s. Again, I cannot say who did what with any authority, but I played a LOT of D&D back then with various people. Were there games that had nothing but a dungeon and some thin backdrop? Yeah, I guess so, but note that the very book the guy quotes is titled "The Underworld and Wilderness Adventures" and interestingly the rule on page 35 actually has 2 separate categories, Dungeon and Underworld (though I am unsure as to what the distinction is intended to be). While 'Town Adventures' are not really discussed as a possibility in D&D that I recall, they certainly were a significant type as well. Heck, I need not go further than pointing out that the JG product "City State of the Invincible Overlord" and its sister product "Wilderlands of High Fantasy" are specifically designed to provide ready made material for non-dungeon adventuring, and they sold really well (for 1970s RPG supplements at least). What I'm saying is, the guy in the video IS saying people played a certain way in the 1970s, and the way he describes is, at best, a distorted view of the actual situation that I can attest to. Beyond that, its entirely inaccurate of him to say we didn't know about the "rule" on Page 35, or the contents of the (much debated I may add) section on time keeping in the 1e DMG. People knew all about it, certainly the competent DMs I was around knew the 1e DMG inside and out! Heck I can probably still quote sections from memory 40 years later. We really didn't care what EGG said about anything.
I will say, there were quite a few Holmes or later Red Box players who were kids who might have played sort of like what the video is talking about. We had a club for instance where you could just bring a character sheet and join a party, usually. Mostly that was just playing TSR modules, and I'm sure many kids that had Basic played that sort of game. I'm unconvinced there's much theoretically to say about that sort of play, as "rocks fall, you're dead!" was also probably a pretty frequent refrain at that level play if you get my drift. Anyone that was really playing a campaign, like what is depicted in Stranger Things, they were not playing something resembling what the video is hypothesizing. At best its conclusions must thus be considered rather dubious! It seems to mix several styles and views about play incoherently, AT BEST.