1. An apparatus for detection of abnormal motion in video stream, the video stream comprises at least one video frame, said at least one video frame comprises: at least one motion vector, each at least one motion vector representing the approximate common movement direction of a sub-part of said at least one video frame; the apparatus comprises: an extraction module for extracting at least one motion vector from the at least one video frame, each at least one motion vector representing the approximate common movement direction of a sub-part of said at least one video frame; a comparison module for receiving at least one statistical model representing motion in the scene captured by the at least one video frame; and detecting abnormal motion in the at least one video frame based on the relation between the at least one motion vector of the at least one video frame and an at least one statistical model.