The paper describes a novel unassisted, fully automatic segmentation technique applicable to colour natural video sequences. The algorithm uses the fast marching method for fast extraction of semantic objects from a frame in a video sequence. These objects are extracted by joint motion and colour analysis. The algorithm handles background in the same way as other objects, thus it does not need global motion compensation. The basic disadvantage of the fast marching method is related to unidirectional motion of an active contour. The new technique overcomes this difficulty by use of an enhancement step consisting in colour processing only. This processing step is performed on a small portion a frame only.