Because you sped through the level too fast to hear it the first time.
Video Sonic Meets MetalSeptember 23, 2011
The other kind of Metal Sonic.
The King of Pop meets the King of Blue Hedgehogs.
video Sonic Jam SessionSeptember 24, 2010
The Tails jam session will be showing up a few seconds later. By: //www.youtube.com/user/brunoguitardreamer
The best Sonic mash-up since Sonic & Knuckles.