Probably got paid to do so. I've noticed it for a while now - since they've become one of the biggest channels on youtube and appeared in news etc they've been mostly doing commercial like videos instead of their usual ones. Lots of stuff for EA for their games etc - that's when I've stopped watching their stuff on a regular basis. They might still try hard to make the vids fun, but in the end it still feels like a commercial to me. Though their recent Zelda video was great.