Video browsing by direct manipulation allows users to smoothly observe objects of interest in a video even if it is not moving uniformly with respect to time. A smooth, controlled dragging on the seeker bar can only result in a uniform browsing if objects are also moving uniformly with respect to time. Otherwise, it is more likely to result in erratic, non-uniform movements.
Hovering the mouse over an object of interest shows a hint path which corresponds to the estimated trajectory of the object. This trajectory visualization could occlude other parts of the object (or even other objects in the video). Besides, if the video is being watched on a tablet, user’s own hand would occlude the object he is most interested in observing.
Direct manipulation of the video could be really useful while observing motion patterns in detail, or while analyzing CCTV footage where objects of interest usually cover only a fraction of the total video recording. However, there should be an alternative option to browse videos in touch devices to avoid possible occlusions.