it looks like the belt is not on the AC tensioner completely. Have you narrowed it down to which belt drive is causing the noise? main or AC?
GT1/ISIS/MoDiC = Factory authorized diagnostic system used by BMW dealerships across the world.
NCS Expert = BMW Factory R&D programming tool available on the internet (not intended for the public and not available to the dealership network)
OEM = Genuine BMW part only available from a franchised BMW dealership.
DME = Engine Management Computer