We study the problem of optimal resource allocation for multi-user wireless video transmissions from an informationtheoretic point of view. We show that the previously known optimal rate allocation solution in wireless multiaccess which maximizes the weighted sum rate is suboptimal in wireless video communications. We further derive the optimal video resource allocation by jointly considering the Application-MACPHY layers. This optimal scheme maximizes the weighted sum video quality of all video users for any feasible power control policy. We refer to this policy as Largest Quality Improvement Highest Possible Rate (LQIHPR). We propose a simple greedy algorithm for implementation. With the help of the inherent prioritization mechanism of video coders, we show that LQIHPR is universally optimal for all video coding schemes. Simulation results demonstrate the significant improvement LQIHPR leads to as opposed to the conventional one.