This paper introduces a Self-Similarity Matrix (SSM) based video copy detection scheme and a Visual Character-String (VCS) descriptor for SSM matching. SSM, which exploits the spatial and temporal information in a video clip, is extracted from exhaustive calculation of distances between the frames. The SSM based method treats the video clip as a whole and transforms the temporal self-similarity into a matrix. Moreover, by implementing the proposed VCS descriptor, the problem of SSM alignment failure and size variation can also be solved properly. Experimental evaluations based on CIVR07 Copy Detection Corpus validate the effectiveness of the proposed solution.