You, uh, DID actually WATCH the ad before you allowed him to put it out there, right? Because while I got a good laugh from it... it wasn't exactly very complimentary towards LoL, or its player base for that matter. Yeah, it was very tongue-in-cheek, but the way it mocked the gameplay as just being a load of clicking without actually telling viewers anything meaningful, snarked about how you can just roll your face on the keyboard, went on about the flame 'n blame culture of the game, and taunted LoL players as people who play because they have nothing to contribute to society didn't make it exactly a very good sell of the game's merits. LilyPichu's ad was a lot better, frankly, and not just because I could listen to her voice forever- it actually made the game sound APPEALING, which I assumed was kind-of the idea.
I mean sure, people are allowed to say whatever they like about the game, and there are hundreds of videos out there on YouTube about how crap LoL is (mostly made by asshole Dota 2 fanboys who can't accept "you have your game and I'll have my game"), but the impression I'm getting is that this is an official partnership between Riot and the YouTubers, so it's kind of weird that you'd endorse an ad for LoL that doesn't actually seem to like it much.