Abstract: The digital watermarking for video is an effective method to protect the video copyright. Based on the previous video watermarking techniques, this paper summarizes their features, classification, attacks being incurred, embedding and extracting/detecting algorithms. The watermark information can be embedded into the video in spatial or frequency domain, or into the compressed video bit-stream directly. And the watermarked video will suffer from some novel attacks that are different from those on image watermarking. Also in this paper, the merits and defects of each algorithm, including robustness, safety, certainty and reliability, are analyzed, and several typical algorithms for embedding and extracting watermark are introduced as examples. In the last section, the key techniques and the development tendency of the video watermarking are discussed.