This paper describes an Augmented Reality (AR) Videoconferencing System, which is a novel remote collaboration tool combining a desktop-based AR system and a videoconference module. The novelty of our system is the combination of these tools with AR applications superimposed on live video background displaying the conference parties' real environment, merging the advantages of the natural face-to-face communication of videoconferencing and AR's interaction capabilities with distributed virtual objects using tangible physical artifacts. The simplicity of the system makes it affordable for everyday use. We explain our system design based on concurrent video streaming, optical tracking and 3D application sharing, and provide experimental proof that it yields superior quality compared to pure video streaming with successive optical tracking from the compressed streams. We demonstrate the system's collaborative features with a volume rendering application that allows users t...