IP and MPEG-4 digital video are two key technologies that will be increasingly combined in the very near future for the deployment of next generation Internet multimedia services. This article discusses technical issues related to the transport and the QoS control of MPEG-4 multimedia applications, such as interactive video-on-demand, over Internet. In particular, it describes the design, implementation and performance evaluation of an experimental Java-based MPEG-4 interactive VOD system over IP DiffServ networks. We demonstrate that Assured Forwarding Per Hop Behavior is a performing candidate for conveying real-time video communications in conjunction with video-aware packet marking and scheduling mechanisms and advanced MPEG-4 DMIF signaling protocol. In this issue, we also propose a Video packet Marking Algorithm for IP Diffserv routers, called DVMA that reduces video packet loss probability and end-to-end transfer delay during network congestion.