In video surveillance systems, one of the key design requirements is that video throughput must not fall below a certain limit as the contents must be adequately perceivable. In this paper, we address the problem of guaranteed transportation of critical video flows in wireless WiMAX mesh networks. Our solution is based on the insight that in seeking to construct optimal routing trees and to maximize the network throughput, the problem of assigning the highest possible data rate to source nodes and that of finding the best and efficient forwarding trees from sources to collection points are not independent, the solution of each has a profound impact on the outcome of the other. Therefore, the two problems should ideally be solved jointly. Both problems are essential for the global system performances, in particular in situations of scarce network resources. In this paper, we formulate the global system optimization as an Integer Linear Program (ILP) that maximizes the network utility while satisfying QoS requirements. We also propose a scalable and yet efficient heuristic Joint Routing and Rate Assignment solution, termed JRRA.