Comparing Let's plays with cinema movies is kinda dumb tbh. and even if you are not claiming to have created the game shown in a Let's Play, the characters of a game don't have a cameo in your videos, your videos are about them. Also keep in mind that you are earning money from the Ad service that YouTube presents not from selling your Let's Play's. That's a huge difference that people tend to forget.
Wreck it Ralph is a product that you bought. Earning money through a product that uses copyrighted assets or characters is illegal unless both companies are okay with it (in other words the creators of the movie have to pay).
Let's Plays is a hobby that you don't buy to watch. Lets Players earn money because they activated ads provided by YouTube not because they sell videos that use copyrighted assets or characters.
If ninty should leech from somebodies money then it's the amount of money that YouTube earns, not the creator of the video.
Though various IP law systems could use a tweak the fact remains it is much the same logic as far as the law is concerned.
What? That does not change a single thing and is functionally identical. I do not pay to watch TV either (well TV license aside) and you can bet TV show makers, that also do not sell their TV show to me, at least until the DVD comes out, are troubled by this.
In fact have a video detailing exactly that (skip to around 2:30).
The Youtube vs Viacom stuff more or less did this, indeed it may well have been what let to this sort of thing we see today.
Nothing you said makes any sense in any reading of any functioning intellectual property system I have ever read up on (and they are all pretty similar in the broad strokes).