Abstract: A method and an apparatus for modifying video signals in such a manner that, when recording said signals with a tape recording apparatus, the control of this apparatus is disturbed, which signals comprise image point signals grouped according to image lines and preceded, in each line, by a line synchronization pulse and a colour synchronization signal, the plurality of lines being combined to a frame preceded by a frame synchronization pulse, the image point signals being situated at one side, and the synchronization pulses at the other side of a zero level, in which additional pulses resembling line synchronization pulses having a deviating shape or situated in deviating points of a frame are added. In particular, in at least a part of the frames, in a number of last lines the normal line synchronization pulses are removed in arbitrary locations, and, instead thereof, additional pulses with a deviating shape, and in particular a shorter duration, are introduced.