Video applications are increasingly popular over smartphones. However, in current cellular systems, the downlink data rate fluctuates and the loss rate can be quite high. We are interested in the scenario where a group of smartphone users, within proximity of each other, are interested in viewing the same video at the same time and are also willing to cooperate with each other. We propose a system that maximizes the video quality by appropriately using all available resources, namely the cellular connections to the phones as well as the device-to- device links that can be established via Bluetooth or WiFi. Key ingredients of our design are: (i) the cooperation among users, (ii) network coding, and (iii) exploiting broadcast in the mobile- to-mobile links. Our approach is grounded on a network utility maximization formulation of the problem. We present numerical results that demonstrate the benefit of our approach, and we implement a prototype on android phones.