In this paper, we define a shot-identifier (we called this shotID) which easily represents characteristics of each shot. The shotID is calculated from positional and color information. And we propose a video retrieval method using the shotID. The proposed method is robust to compression, format conversion, frame dropping and noise such as watermark and so on. Furthermore, we realize a copyright protection system for digital video with watermarking technique using ideas from spread spectrum communications based on our retrieval method.