It's the default boot animation of Cyanogenmod 11 (a custom ROM for Android devices, for those who don't know), but with Rainbow Dash's head instead of Cyanogenmod's mascot. Kinda fitting as they're both cyan.
(Also notice the beginning of the animation, Dash goes from smiley face to frowny face if you missed it. Seems it skips the intro when you reload, skipping directly to the looping part, I should probably make a gif or something and/or show it on Youtube.)
You can download the bootanimation.zip here to put it on your phone in /system/media (make sure to chmod 655 it): www.mediafire.com/download/mu3…
Been tested on a Samsung Galaxy Note, it should work on most phones, if you're confused you'll probably find good tutorials on the internets about it. Note that you'll probably have to root your phone first and mount /system read-write.
Here's Tumblr-friendly GIFs you can reblog: blog.juju2143.ca/post/98335448…
for Dashie's very legal puppet: tiredbrony.deviantart.com/art/…
Creativity Kitchen because they're pretty cool and helpful (support
's Dinky's Destiny! >.>)
Myself for everything else
The Cyanogenmod Team for designing the awesome original boot animation found on Cyanogenmod 11
Lauren Faust, Hasbro and DHX for My Little Pony: Friendship is Magic and its very relatable characters