A video recorder connected to a plurality of cameras and a plurality of client devices and a method of controlling the video recorder are provided. The method includes: setting a plurality of buffers, in a memory of the video recorder, corresponding to the plurality of cameras, respectively, and setting a plurality of positions in at least one buffer of the buffers for loading image data input from a corresponding camera of the plurality of cameras; loading, in the at least one buffer, the image data on given positions of the plurality of positions; and transmitting the loaded image data to the plurality of client devices so that each of the plurality of client devices receives the image data input from a same corresponding camera.