Simultaneous support of multiple delay-critical application sessions such as multiuser video streaming require a paradigm shift in the design of ad-hoc wireless networks. Instead of the conventional layered approach, cross-layer optimization is needed for more efficient resource allocation, across the protocol stack and among multiple users. In this work, we extend our previous effort in joint capacity and flow assignment at the MAC and network layers, to include rate allocation at the application layer of each user. The proposed optimization aims to minimize the tradeoff between encoded video quality of all users versus overall network congestion. Compared to a scheme with oblivious layers, where capacity, flow and video rates are assigned individually, simulation results show significant performance gain of our proposed cross-layer approach, in terms of maximum sustainable rate and quality of the video streams.