"Actual gameplay footage slowed down to emphasize PhysX effects," the video notes. BOOM video 1270
Those PhysX effects are purely optional, designer Fredrik Thylander confirmed alongside the minimum system requirements in the On Mirror's Edge forums:
Operating System Microsoft Windows XP SP2 / Vista
Processor Intel Pentium 4 3.0GHz or 100% compatible equivalent
Memory 1GB RAM
Video Card 256MB memory with Shader Model 3.0
HDD Space 8GB
DVD Drive 1x DVD Drive
Soundcard Soundcard with DirectX 9.0c compatibility
DirectX DirectX 9.0c
Network An online connection is required for access to Leaderboards
The PC version of Mirror's Edge hits North America on January 13.
Thanks to Shacker SlamDunk for the heads up.