The Berlin based design agency Fork Unstable Media is releasing a software based video mixing application (mac only).
shprootCell v1.7 based on quicktime. (no flash movies)
For all you wannabe or future VJs out there who cannot afford a hardware sollution, pimp your videoram and get this one.
shprootCell v1.7 is a Quicktime based video mixer for live-usage; Including features like crossfading between 2 sources, video-sound-sync, and different blending-modes. It furthermore provides a customizeable sound-reactive text and shape generator and various sprutzel enhancements
shprootCell_v1.7 is open source (max4 patcher included).