The ground conductor is part of a ground loop that also includes your coaxial shield conductor. The path of the capacitively induced extraneous current is the same as that shown for broadcast interference in figure 3. Again, the video cable shield conductor is carrying an extraneous current that the center conductor is not. Hence, there is an undesirable voltage difference between the two conductors at the monitor input and it will be displayed as interference. A ground loop serving as a loop antenna, introducing RF interference to your video.
Ground loops can cause one signal to interfere with another.
Therefore, there is an undesirable voltage difference between the two conductors at the monitor input and it will be displayed as cross-talk interference. The video and power industries have each designed their systems and equipment independently. As a result, there's a degree of incompatibility. Ground loop interference is a consequence. Two long coaxial cable shields each provide a return path for the signal in either center conductor.