Lodum said:
The "we don't want people to spoil themselves!" justification is pretty dumb, but... well, it sounds better PR-wise than the reason I'd give: "We don't want freeloaders watching the story of our story-heavy game on Youtube instead of buying it themselves". Though, frankly, I don't care if companies decide they don't want their game streamed/Let's Played/etc and am perfectly okay with them copyright striking your channel if you decide to anyway.
I hope that one of these cases goes to court at some point, I'd love to at least have what's legal/not in writing, regardless of which way it goes. Though, I hope it goes to the company making the thing in the first place and not the "personality" streaming it.
If it matters, I don't think Let's Plays are Fair Use and if a company wants to not allow them, good for them. LPs might drive attention and sales or they might not, and I think it's the company's prerogative to decide if they want to allow them.
http://www.thatdragoncancer.com/thatdragoncancer/2016/3/24/on-lets-plays
There is a compelling argument for Fair Use on Lets Plays though. Competitive Chess has been a tinder box overflowing with claims, suits, and attempts to lock down or control what is broadcast from the matches. Originally it started with the company that owned the chess board claiming a violation of their copyright that the world championships were being broadcasted without their consent or control- and more recently with attempts to prevent outlets from broadcasting the moves made during the match with commentary and analysis. These attempts have been shot down or otherwise blocked by judges, making the statement that act of playing a game of chess is a transformative work that generates it's own copyright in control of the players, broadcasters, or other parties previously agreed to by those involved without violating or harming the copyright of the game.
Now the question is how far should that idea or argument reach? If a recording or broadcasting of a game of chess isn't a violation of the copyright on the game itself when played at the professional level, what about when it is played with amateur players? Does this argument protect the recordings of Garry Kasparov Vs Deep Blue, when a person played a computer at chess? What about if we no longer have the game of chess played on a physical board and instead played on a computer or electronic device? Does this argument only protect Chess as it is named, or does it extend to all board games?
If the argument does extend to playing at the amateur level, playing against a computer and not another person, covering all board games and not just Chess, and covers said games no matter if they are physical or digital versions- then why wouldn't said argument also reach video games?
Though video games do have movie elements in cutscenes, music, and story elements, though they may involve a lot of reading like a book, they are not defined by the media they are consumed on. The Video portion of the name isn't the defining factor of a video game, it is the Game component.
Lifting a game wholesale and making it available yourself, such as through distributing a video game through the internet so people can gain a copy of it without purchasing it (and doing so without consent of the copyright holder) is a violation of the copyright on that video game. That as uploading a complete movie to Youtube for people to watch, or dumping a book into Googledocs, a violation of copyright. But a non-interactive copy of media, such as a video recording or broadcast, of an interactive media can be argued to be protected as a transformative work, that the act of playing an interactive media creates a unique copyright for the player each time it is played and the new copyright created is what governs the recordings of that play, not the original copyright on the video game itself- that the copyright on interactive media does not permit control over non-interactive media recordings of that interactive media.
Even then, this gets muddy when we ask where that line is drawn. For example, if someone was exclude all recordings of interactive sections of the game to have only non-interactive sections and elements in the video then upload it to Youtube, would that need to be treated as uploading a whole movie to Youtube and seen as a violation of the video game's copyright, or would that need to be treated as if someone cut or edited a movie down to a collage or collection of clips and uploaded that and decide if or how that violated copyrights? How much of the game needs to have interactive elements for it to fall under this argument?
All I can say for certain is that if it does go to court and the court finds that recording yourself playing a video game isn't a transformative use of the video game's copyright and that Let's Plays are not a reasonable form of commentary on the media that is copyright protected then that will be a massive hammer that has impacts far beyond the streaming of video games and Youtube videos of video games.