A video processing system includes at least one video source, a region selecting unit, a subtracting unit and a display unit. The region-selecting unit selects the user-defined region of interest from the video source. The subtracting unit subtracts the required region, selected by the region selecting unit. The output of the subtracting unit is provided to the display unit, which displays the required output. In one embodiment, when video data is received from a plurality of video sources, the selecting of user defined regions of interest from the video sources is supported. The region subtracting unit can be used to subtract the required region of interest from video data and it is displayed on the display unit. In other embodiments of invention, the display unit displays on overlay of two unrelated video streams.