1. A method for use in real-time insertion of visual effects in a video stream, the method comprising: i. processing at least one reference image that contains a region of interest, which is to be involved in the video stream, said processing comprising defining a set of at least a few reference features in said at least one reference image, and inserting the visual effects into said at least one reference image with a desired orientation of said visual effects with respect to the region of interest in said reference image; ii. grabbing successive video frames in a sequence of a few video frames from said video stream, and selecting at least one of said video frames to be used as at least one snapshot image; iii. processing said one or more snapshot images by selecting therein at least two features from said at least few reference features and determining a reference transformation between the snapshot image and the reference image; and independent of said processing of the snapshot image, applying processing to the snapshot image and to other of said sequence of the video frames to determine a sequence of transformations between them, iv. utilizing said determined sequence of transformations and said determined reference transformation to determine an operative transformation between the reference image and either one of said few video frames in the sequence, thereby enabling real-time management of the appearance of the visual effects in the video stream by using said operative transformation for the insertion of the visual effects in other video frames.