This paper presents an oblivious real-time video watermarking scheme in which extended m-sequences is selected as watermark pattern. The good balance property of extended m-sequences is exploited to generate a stable reference point, which can be used to accurately compute modified amount between the watermarked and the original vide in the case of original's absence, and furthermore, it helps to improve the robustness of watermarking scheme. To satisfy the real-time requirement, the processes of watermarking embedding and detection are directly operated in the variable length codeword (VLC) domain. To acquire better visual quality, the human visual system (HVS) is used to control the modification strength. Under the premise of assuring better visual quality and real-time requirements, our scheme is more robust than the schemes proposed by Lu and Frank et al..