2 system of claim 1, where the processor is programed to determine that an object in the video has motion satisfying the threshold by determinathion that the object has a motion vector whose magnitude is at least equal to a line magnitude.
2. The system of claim 1, wherein the processor is programmed to determine that an object in the video has motion satisfying the threshold by determining that the object has a motion vector with a magnitude at least equal to a threshold magnitude.