I don't see what's so wrong about Nintendo's way here. They could just pull the plug if they wanted, and take down anything that features their content. But that's not what they're doing here...they're literally saying "Hey, we support you doing this, but since this features our content, we want a share of the profits too," which is the best possible way to handle it as a business. They'll still get whatever little extra stragglers they didn't get with their AAA advertisement plans, and if not, they at least got some of the ad revenue from them taking a peek.
It's not really that simple. The deal Nintendo offers here is pretty bad, and that says something considering Nintendo has been one of the most aggressive companies when it comes to making copyright claims on videos and so on. Anyways, this affiliate program offers a deal in which Nintendo and the content creators (Let's Players, video critics and Youtubers using game footage in general) share the profits from the ad revenue earned by their videos. The thing is, Nintendo takes a significant share, one that on top of a lot of other problems that I will explain shortly, in a way makes it almost non-profitable to the ones actually creating these videos. And in a lot of cases we're talking about people who put a significant amount of work into their content, regardless of what you and I personally may think about Let's Plays.
Their deal states that the cut Nintendo will take is either 60% or 70%, for single videos or for entire channels respectively (you can apparently register both, though if you go with the channel it sounds like you can't ever post or mention anything about non-Nintendo products, but I'm not sure on that one). Nintendo will pay out using Paypal only, and in US Dollars. That's a problem because it means that on top of the big cut Nintendo are taking, the Youtubers then have to pay currency exchange rates depending on where they live, which might not sound like an issue but please remember that most Youtubers doesn't earn a lot of money on their videos. Any cut will hurt. Being a Youtuber, regardless of how ridiculous it may sound, has quickly become a serious profession, and these restrictions are actively working against it. It doesn't help that Nintendo makes sure to say that these percentages can be changed at any time without notice. Doesn't sound like good faith to me.
I don't believe this cut, or their deal in general is reasonable, especially considering that Google already takes a cut from every single video you make, and while their cut isn't small, it's still smaller than Nintendo's. I'm not sure what the number is though. Since they're using Paypal it means that Paypal will have its fees as well, and it sounds like Nintendo aren't going to be paying those. There are a lot of other cuts taken as well, though I'm not sure how all of this works as I'm not someone who makes Youtube videos for a living.
And like I said earlier, there's not one shred of evidence that Youtube videos will take away from the number of sold copies, but there is evidence that they can, and have sold copies and worked as free advertisement. Anyways, I'm not sure if this was linked earlier or not, but TotalBiscuit explains this a lot better than I can, if you want to get a bit more in-depth of an explenation I reccomend watching the first topic he discusses in this video. It's the first 11 minutes or so:
https://www.youtube....h?v=t-67CvWTQ0I