IANAL but it's probably covered by fair use. Otherwise "Let's Play Videos" on YouTube would not be possible(and they actually show all the content in the game, while this shows single screenshots). Same goes for games review sites, Metacritic, game wikis etc that all have screenshots. It's definitely not in the interest of a game publisher to disallow the internet to show off their game, but they probably can't legally stop it either way.
Let's Play videos only exist because publishers allow them to. They aren't fair use. They could drop the DMCA hammer tomorrow but they don't because it makes them money.
Edit: obviously I'm not supporting this but this is the legal reality.
There are differing opinions on this from what I've heard. If the let's play video competes with the experience of playing the game then it seems like it would be as you say, but for many cases that would probably not be true. This is still not decided in court though and just because someone can DMCA someone else does not mean they are in the right legally. It would also be different in different countries, the free use doctrine and DMCA are a American concepts.
Virtual youtubers had numerous copyright infringement disputes with Japanese game studios for playing video games on stream.
Hololive[1], the biggest vtubers agency, had to settle agreements (and pay money) with Nintendo, Konami, and capcom.
