To cope with vastly increased unique IP addresses demand, an IPv6 specification with enhanced QoS capabilities was standardized by IETF. However, an effective interface for the priority mapping between the video application and RTP protocol is still required for the QoS provision of IPv6 networks. In addition, involving IPv6 based wireless networks, how to decide a suitable video payload length is still a trade-off problem. Therefore, this paper first proposes a Payload Priority field into the video packet header of application layer for providing sufficient priority information to the lower OSI layers. Moreover, this work develops an adaptive packetization mechanism integrated with scalable video coding for providing unequal error protection to the layered video data. Furthermore, a simplified IPv6 multimedia platform that comprises of a video streaming server, video clients, and an AAA server is implemented. Through simulations with different video sources, the proposed mechanism shows great efficiency and strength.