Actually, it doesn't feel like the money from Minecraft's success is being use as fuel for game development. Sure Mojang released a few games in cooperation with other teams. But their real next game, 0x0001c (I can never spell it correctly), is in pause due to Notch not being motivated enough.
Last I checked the policy, some went to Google but most to the producer. It's a pretty significant cut, some people make their living off of Youtube. Minecraft is very popular with many successful Youtube "stars", if Mojang were to take a cut there would be a lot of vocal dissatisfaction.
Apparently what they mean by "ensure Nintendo content is shared across social media channels in an appropriate and safe way" is roughly "safe means we make money off it"
So it's cool to see Notch mention that he had the same opportunity and didn't take it.
Money matters, but "safe" also means that it's not shown in inappropriate places or remixed with inappropriate content. For a family-friendly brand like Nintendo, that's a big deal. Advertisers care a lot about this, too, even though that's less relevant for Nintendo.
It'd just be more cash to fuel game development.