Currently, various types of video data are being transmitted over networks. One of the momentous challenges in video data transmission is continuous QoS (Quality of Service) support over heterogeneous networks. Two types of approaches to guarantee the QoS of video traffic over networks exist: prioritized video data fragmentation and QoS-aware packet classification on MAC. In this paper, we suggest a cross-layer architecture for delivering data-partitioned H.264 traffic over heterogeneous networks. Our proposed scheme deals with H.264 data-partitioned video traffic as service classes of IEEE 802.16d WiMax and CBQ (Class Based Queuing) priorities of WAN (wide area network). To guarantee the QoS of transmitting H.264 data partition A, we classify H.264 video traffic based on importance and assign a high-priority service class (rtPS) and high CBQ priority to data partition A. The simulation results reveal that our cross-layer QoS architecture is able to guarantee QoS for high-priority video traffic on WiMax-implemented heterogeneous networks.