With the advances in image based rendering (IBR) in recent years, generation of a realistic arbitrary view of a scene from a number of original views has become cheaper and faster. One of the main applications of this progress has emerged as free-view TV(FTV), where TV-viewers select freely the viewing position and angle via IBR on the transmitted multiview video. Noting that the TV-viewer might record a personal video for this arbitrarily selected view and misuse this content, it is apparent that copyright and copy protection problems also exist and should be solved for FTV. In this paper, we focus on this newly emerged problem by proposing a watermarking method for free-view video. The watermark is embedded into every frame of multiple views by exploiting the spatial masking properties of the human visual system. Assuming that the position and rotation of the virtual camera is known, the proposed method extracts the watermark successfully from an arbitrarily generated virtual image. In order to extend the method for the case of an unknown virtual camera position and rotation, the transformations on the watermark pattern due to image based rendering operations are analyzed. Based upon this analysis, camera position and homography estimation methods are proposed for the virtual camera. The encouraging simulation results promise not only a novel method, but also a new direction for watermarking research.