Presenting more comprehensive information than key frame and any subset of frames, mosaic has attracted a growing attention in recent years as a useful element for a variety of vision tasks. In this paper, we present an efficient approach to video mosaicing based on motion analysis with investigating two important issues that significantly affect the performance of mosaicing. First, given a video shot, a method based on motion entropy analysis is introduced to determine whether the visual content in a shot or video segment is suited to be represented by a mosaic. The second is to decide which subset of frames in the shot is the best to be selected for efficient and effective mosaicing by constructing a global motion path. Experimental comparisons with typical mosaicing method approve that with this approach, the visual quality of mosaic is significantly improved, as well as the computation time is remarkably reduced.