Finally, after spending entirely too much time on this, it's done!
The Cutie Mark Crusaders, performing the chorus from "Beep Beep", by Schnuffel Bunny
Entire thing (rigs, backgrounds, animation) created in Flash CS5 by me.
EDIT: sorry, sync wasn't working for too many people. Here's the version without seamless looping on the audio, because desync is more distracting than that.
EDIT2: Now with better (stereo!) audio!
"Beep Beep" is © Jamster/Jamba! ringtones - original audio from here: [link]
and the Cutie Mark Crusaders are of course ©
Animation by me!
On Youtube in 1080p: [link]
On EquestriaDaily! [link]