The song is from episode 2 of Community.
Original clip here: https://www.youtube.com/watch?v=j25tkxg5Vws

As seen in PONIES the Anthology II. It took one full week of 12-13 hour days to make. However, it would not have been possible without these amazing artists whose vectors I used. I didn't ask permission for many of them so please make up for it by checking out their deviant art accounts.

First up is M99moron who actually made several custom vectors specifically for this video. He's a champ for putting up with what must have sounded like some very odd requests.
http://m99moron.deviantart.com/
Vectors Provided: Moustaches, Disco Ball, Turntable, Potato (regular and frozen), Bucket of Lard

And thank you arctickiwi for providing an altered version of your ice cream vector.
Vector Provided: Ice Cream
http://arctickiwi.deviantart.com/

And here are all the rest of the artists who were not informed of my use of their material. I apologize if you would have rathered me to ask first but I was short on time.

http://bronyboy.deviantart.com/
Vector Provided: Smarty Pants Doll

http://lord-giampietro.deviantart.com/
Vector Provided: The DJ PON-3 glasses on the spider

http://daafroman.deviantart.com/
Vector Provided: Twilight's Library

http://blackgryph0n.deviantart.com/
Vector Provided: Celestia's Cutie Mark

http://danton-damnark.deviantart.com/
Vector Provided: Nightmare Night Spider

http://myythic.deviantart.com/
Vector Provided: Twilight Sparkle Derp

http://capt-nemo.deviantart.com/
Vector Provided: The Vinyl Scratch Glasses on Pinkie

http://atomicgreymon.deviantart.com/
Vector Provided: Winona

http://sircinnamon.deviantart.com/ (I'm sorry, I forgot to mention your name for inclusion in the Anthology credits)
Vector Provided: The Goat

http://ironhooves.deviantart.com/ (sorry for the late credit to you as well)
Picture Provided: Bueno Fluttershy

Visit the Anthology II tumblr.
http://anthology2.tumblr.com/

Download link for the video:
http://dz-studios.com/silksk/Anthology%20II/Fluttershy%20is%20The%20Disco%20Spider.mp4