Ehhhhh I don't see anybody else pointing it out, so I guess I'll do it. I guess a lot of people don't exactly "get" BOTH Tumblr and 4chan references, so I don't see it mentioned. Dan is making fun of those who criticize films and have usually the same kind of slang and attitudes as those on 4chan, that are easily offended and opinionated about films. (Theres a distinct overlap). But the thing he is saying: "REEE" is a reference to how these type of angry, bitter, easily-offended 4channers are called "Autists" and are compared to autistic people. That the tantrums they go on are similar to those kind of episodes that autistic people experience. So congratulations, everybody, Dan just made fun of autistic people, yay.
Then again, Dan doesn't mean that, obviously, he's just making fun of 4channers, but it's interesting how he uses this "language" but not everyone gets where it originates. This draws back to how he can't make toast without someone finding him problematic and that's. That's the way of the internet, Dan. I'm just surprised there hasn't been upset people, he's using referencing that's... Kind of sensitive. Also, I guess this is another instance of him trying to appeal to the edgy, meme demographic of teenage boys.