The site specifically responds to several swear words and they're present in the source code. If this were a promotional site for a new children's cartoon series, I doubt they'll even have such words in the site source code.
Also, there's nothing in the linked video saying where this clip comes from aside from a link to the /co/ board in 8chan. Knowing chan culture, it wouldn't be too far fetched that the people there would go to insane lengths just to troll people.
I may be wrong (and I'm happy to be wrong about this), but I'm leaning towards the theory that this is an elaborate prank, especially with April 1 coming up in two weeks.
EDIT: Hmmm... [http://warburtonlabs.blogspot.com/2012/11/another-sketchbook-thats-full-of-it.html]
Nope, still leaning towards April Fools prank. That thing was three years ago.