Play it from the disk right? pop the disk in and play it. Hell I didn't know you could play it without the disk. Herpderp. Thanks!
You misunderstand what he's saying. The first time you put the disc in the 360 it will load some files onto your Harddrive to reduce load-time. You can manually remove these and cause the game to pull them off from the disc each time they are used; i.e. "Play it from the disc"
Edit: This action has been noted to increase texture quality and fix some bugs at the expense of load time and noise (your disc is always spinning).