An effective video watermarking algorithm is proposed to protect the copyright. The watermarking procedure is based on a three-dimensional discrete wavelet transform (3D DWT) and spread spectrum sequences. Two perceptual binary watermarks are preprocessed using mixing and pseudorandom permutation. After dividing the video sequence into video shots, the 3D DWT is performed, then the preprocessed watermarks are embedded into the 3D DWT coefficients, while considering robustness and invisibility, using two spread spectrum sequences defined as the user key. Experimental results show that the watermarked frames are subjectively indistinguishable from the original frames, plus the proposed video watermarking algorithm is sufficiently robust against such attacks as low pass filtering, frame dropping, frame average, and MPEG coding.