EffecTV is a real-time software video effect processor based on motion detection and image processing techniques. EffecTV was released in 2001 as an open source software, and has been growing the number of features and effects through contributions from the open source community. EffecTV has been used for various purpose - desktop toy applications, by visual jockeys (VJs), in theatrical plays and other stage performances. In this paper, we describe the implementation of EffecTV and some case studies.