NoCD cracks are not outlawed. In fact a NoCD is necessary to get the original disc version of Black Mirror working on Vista, Windows 7, and Windows 8 because the old version of StarForce copy "protection" used on the Black Mirror discs does not function with Vista, Windows 7, and Windows 8.
Changing video drivers won't help with problems caused by copy "protection." If anyone told you it would, they are giving you a runaround.
I do not know who or what "ag" is, but if you bought a download version of the game and "ag" is the name of the company hosting the download, a NoCD would not help you anyway. Download versions don't use disc-based copy "protection" because there is no disc.
If you want a download version, Gamersgate does offer onehttp://www.gamersgate.com/DD-BLMI/black-mirror