This video is from the same M3 V8 that I just put the throttle actuator and idle actuator  in the car,,,,he was complaining about a noise inside the engine compartment,,,,,I think you can hear it plan as day,,,,the problem was both a/c pulleys were squeezing,,,,I would have gotten some pictures but there is no room for pictures by the drive belts,,,,,when checking for pulpy noise,,,,a couple of things to do,,,,you can spray some lube or WD 40 on the belt and see if the noise goes away or changes pitch,,,,if that doesn’t work,,,,then you have to pop off those plastic covers on pulleys and again use some WD40 and spray a little at the bearings of the pulley,,,,,while the engine is OFF please,,,,,don’t want to lose any fingers,,,,just spray each pulley one at a time until the noise goes away,,,,then you have found your noises pulley.