He would Hoo all the time but he doesn't even hee hee anymore :(

I think it's taking it literally i.e. people who don't know made the picture on the left, people who do know made the picture on the right

It's a stupid meta-joke. The video is how to turn color illustrations into a moody B&W.

Hint: This one doesn't actually require outside knowledge. It might click if you re-read it.

Someone needs to really break this one down.

Hint: try reading the meme again. It doesn't take outside knowledge, lol