The present invention is in the field of Content protection, most particularly in cinema venues where camcorder acquisition followed by immediate illegal distribution creates important revenue losses for content owners. It is known that anti-camcorder systems using a color modulation can be circumvented by using low shutter speed in the camcorder. Today, the shutter speed is determined automatically by the camcorder as a function of the filmed video source. In automatic configurations, shutter speed self-adapts to either motion, or flicker detection, both of which taking into account brightness variations only. The proposed invention proposes a dual color/brightness modulation to defeat automatic shutter speed adjustment. For example, a color modulation at 50/60 Hz is carried out and a brightness modulation at a higher frequency 100/120 Hz is added to force the camcorder to work at a high shutter speed.