The segmentation of objects in video sequences constitutes a prerequisite for numerous applications ranging from computer vision tasks to second-generation video coding.We propose an approach for segmenting video objects based on motion cues. To estimate motion we employ the 3D structure tensor, an operator that provides reliable results by integrating information from a number of consecutive video frames. We present a new hierarchical algorithm, embedding the structure tensor into a multiresolution framework to allow the estimation of large velocities.The motion estimates are included as an external force into a geodesic active contour model, thus stopping the evolving curve at the moving object's boundary. A level set-based implementation allows the simultaneous segmentation of several objects.As an application based on our object segmentation approach we provide a video object classification system. Curvature features of the object contour are matched by means of a curvature scale space technique to a database containing preprocessed views of prototypical objects.We provide encouraging experimental results calculated on synthetic and real-world video sequences to demonstrate the performance of our algorithms.