This paper proposes a trajectory-based video retrieval system to retrieve desired videos from a video database through string matching. First, in order to represent each trajectory, a hybrid technique is proposed for representing its semantic meanings and geometrical properties. At this scheme, we use the Bezier basis functions to interpolate some lost control points of each represented trajectory. Then, the distance between any two trajectories can be measured by comparing the positions of sampling points extracted along their Bezier approximations. In addition, this hybrid method uses a novel labeling technique for converting a trajectory into a string. This string representation can give more semantic information in interpreting a trajectory and make important improvements in video classification. More importantly, the problem of partial matching will become easy and can be efficiently solved by a string matching technique. Experimental results have proved the superiority of our proposed method.