The dynamically changing set of multimedia capable devices in the vicinity of a user can be leveraged to create new ways of experiencing multimedia applications through migrating parts of running multimedia applications to the most suited devices. This paper addresses one of the core challenges of application migration, i.e., migration of transport protocol state that is maintained by the endpoints of established connections. Our solution fulfills the stringent temporal requirements of multimedia applications and enables migratable applications to interact with legacy applications, e.g., a migratable video player together with YouTube. The core idea of our solution, called SOCKMAN, is to provide a middleware service to hide that proxy-based forwarding is used to migrate connection endpoints, i.e. sockets, and to maintain an end-to-end perspective for the applications. The evaluation of the SOCKMAN implementation shows that SOCKMAN meets multimedia application requirements, preserves transport protocol state, and performs well on low-end devices, like mobile phones.