The First 15 Minutes of Sonic Adventure 2 (Dreamcast)

Copied from MobyGames:

Sonic has returned! This time, his nemesis Dr. Eggman has teamed up with Shadow, a dark hedgehog with a mysterious past, and is aiming once again (like he doesn't) to rule the entire world with the power of the Chaos Emeralds! It's up to Sonic and his friends to stop Eggman and put him out of business for good!

With new features such as a storyline told from the view of both the good guys and the villains, greater speed, and an improved A-Life system, Sonic Adventure 2 is poised to be Sonic's greatest and most dangerous mission yet!