It's Portal magic
Zachariah Scott spent six months tooling around Source Filmmaker to produce a music video that would make every other amateur filmmaker his b*tch. Was he successful? Let me check one more time just to be certain...
Yes. Yes, he was.
To download an mp3 of "The Turret Anthem," hit up the SoundCloud page of the song's composer, Lars Erik Fjøsne.
The Turret Anthem [Steam Community]