1. A video masking processing method, comprising: detecting a masking area to be masked in a frame constituting a video; masking an image in the detected masking area; inserting masking information on the masked image into a predetermined pixel area of the frame; storing the frame comprising the inserted masking information; displaying a vehicle plate number or a human face included in the video using the inserted masking information; and when one of the vehicle plate number or human face is selected, reproducing a frame of the video that includes the selected vehicle plate number or human face, wherein the masking information comprises information on a number of masking areas in the frame, and masking area information corresponding to the number of the masking areas, wherein the masking area information comprises an identifier of a corresponding masking area, information on a masking technique code applied to the corresponding masking area, coordinates information of a left upper point of the corresponding masking area, and coordinates information of a right lower point of the corresponding masking area, and wherein the image in the detected masking area is masked using a different key according to an object type of the image.