I'm probably not going to do this one because I don't watch that much YouTube anymore
EDIT: but I read and HAVE watched some videos so I DO want to do this one. Just have to get around to doing it after the "Rider" series.

At least, not as much as I used to. And the YouTubers I used to watch have also changed their channels from what they used to do.

ANYWAAAYYY~
(Also, I've put literally NO thought into this XD)

Pretty much BlueVacktor stops being so emotional for some strange reason, and turns more emotionless and cold. At least when he's Blue, he was at least somewhat happy, even if he was super duper emotional. Pink hasn't been around much, Green hasn't seemed to notice, and Red has been so busy lately he's hardly home at the Vacktor house. That leaves Yellow (and Purple, technically) to try and figure out what's wrong with Blue, even if I costs Yellow his own happiness and color to make Blue blue again.

(Picture credit goes to Sarcastic-Acid on DeviantART)