1. A method of resizing digital video, the method comprising: converting a source area in a first video frame having a first spatial resolution into a macroblock in a corresponding second video frame having a second spatial resolution smaller than the first spatial resolution; calculating a dispersion metric for a set of motion vectors corresponding to the source area at the first spatial resolution; and performing a motion-vector search configured based on the dispersion metric to find a motion vector for the macroblock at the second spatial resolution.