Abstract: A video signal is modified so that a television/receiver still produces a normal picture from the modified signal, whereas videotape recording of this signal produces generally unacceptable pictures. Videotape recorders have an automatic gain control circuit (FIG. 2) which measures the sync pulse level in a video signal and develops a gain control correction signal for keeping the video applied to an FM modulator in the videotape recording system at a fixed predetermined level. A portion of the back porch intervals following the trailing edges of a substantial number of sync pulses are significantly raised and lowered to improve the playability of the original signal without reducing the effectiveness of the copy protection of the copied signal.