I think this video overstates the importance of YT celebrities, but if you replace that with "hype" it makes a valid point.
Hype is such an important factor for consoles, while PS4 didn't have PewDiePie, it basically had the internet, the internet led to the mainstream media and the mainstream media led to the average consumer. It had a clear message which was "PS4, most powerful console, cheaper than XBox One, not always online, no DRM". They didn't show off the box, which led to both annoyance and more hype for E3 before unleashing the above. It was a perfect storm of hype.
The Wii U, on the other hand, was revealed to absolute confusion both from the gaming media and enthusiasts alike. Was it a controller for the Wii? Was it a new console? It raised questions, but not in a theoretical "what can we expect?" sense, but a "I have no idea what the message is" sense. When the hardware specs started leaking and people realised the hardware wasn't much better than what they had and the cost was just too high, the hype died and never recovered because it never really fixed the mistakes. It wasn't the most powerful console, nor was it a gimmick that was new and exciting.
Like I said, PewDiePie and Youtubers impact is way overestimated, but the valid point is that hype can push a product to stupid levels or kill a product dead. It doesn't matter what the catalyst is.