The invention discloses a video extender, a control method for the video extender, and a coaxial video control transmission device. The video extender comprises a reverse-control extraction module, a closed-loop inhibition module, a reverse-control stacking module and a video driving module, wherein the four modules are matched with each other; amplification and transmission of a video signal from a video signal input end to a video signal output end when in a non-blanking area can be realized; when the video signal is in a blanking area and controlled reversely, a reverse-control signal can be extracted from the video signal output end, and transmitted to the video signal input end; interference on the extraction process of the current reverse-control signal due to the fact that the reverse-control signal sent to the video signal input end is amplified through a video driving module can be avoided; therefore, the positive feedback effect is avoided; transmission of the video signal and extraction of the reverse-control signal can be realized without a processor having analog-digital and digital-analog conversion functions; therefore, the structure of the video extender is simple; and the cost is reduced.