He mentions production numbers, but misses that a lot of these guns died in the wars they were made for.
He also fails to account for increased demand which is the real driver of the price increases.
But it's called supply and demand for a reason. The supply of everything except the SKS is fixed because they're no longer being made. However, even though China still makes their Type 56 Rifle, they cannot import them into the US, so that fixes the supply that matters to us. Mosin imports are likewise blocked.
The guns mentioned are:
German marked K.98k
The first two on this list are subject to people who must have every variation and color. Lots of people have multiple examples. If you can afford more than one, you can certainly afford to outbid most people on a single example. Every time someone is willing to pay more for a single example, it tends to raise the prices on all examples.
This is demand in a nut shell.
Something is only worth what someone else is willing to pay for it.
The SKS is a tougher nut to crack. He shows a Yugo PAP 59/66A1, but talks about the total supply of SKS's.
The Mosin thing caught everyone by surprise, to be honest. The things were ubiquitous. So common you started to suspect that ATF had made it a requirement for having an FFL. "Everything seems to be in order, but where's your 91/30?" They were common and the prices were set pretty low because a. there are a bunch of them and b. the only people who really wanted one were people who couldn't afford a better rifle in one bite.
Cheap guns are gateway drugs. Once you have that first, cheap, gun you get the itch for something better. Even when you have an expensive gun, the monkey on your back whispers in your ear about the grass being greenest over the septic tank.
In essence, prices might come down some, but probably won't recover back to pre-panic levels. There's gobs of new shooters out there thanks to the panicking. I know this because ranges we used to have the run of, now have wait times.
Something else to bear in mind about the price of guns is inflation. With a real inflation rate pushing 12%, some of the "overpriced" guns mentioned have actually lost value if you calculate the purchase price parity with even 8 years ago.