Level Up Labs co-founder Lars Doucet has created and deployed a Wikia directory page called WhoLetsPlay that informs video content creators which publishers allow monetized Let's Play videos and which do not. The Wikia page divides publishers into three groups:
YES - Allows Let's Play AND allows them to be monetized.
MAYBE - Might allow monetization under some circumstances, or it is unknown.
No - Does not allow monetization.
Doucet acknowledges that the situation is a little more complicated than his page might indicate because many of the copyright claims being filed against content creators are the result of YouTube's ContentID system automatically flagging music.
"Right now, there's an issue with music," Doucet said. "Many developers, small and large, license music non-exclusively. This means the musician owns the music, but gives the developers some rights (namely to use it in their game). This means that *technically* it's not legally clear-cut (again, I'm not a lawyer) that the developer has the right to grant permission for fans to make monetized videos that include the music."
"This ambiguity leads to situations where 3rd party licensors and YouTube can actually issue takedown notices and content-ID matches to developers for hosting THEIR OWN OFFICIAL TRAILERS or THEIR OWN MUSIC, in order to 'protect them. Insane, right?" he added.
Doucet said that this bad in the long-term because it will force developers to secure exclusive music rights as a means to protect themselves. As a general rule, exclusive rights tend to be more expensive for developers and not as flexible for musicians.
YouTube's solution is that Let's Play and other video game-related content creators make videos without music. Doucet said he may also create a second wiki for "known bad actors" in the music reseller space, but doesn't want it to become a "witch hunt."
You can check out the Wikia page here.