The widespread popularity of roaming wireless devices with limited and heterogeneous capabilities is enabling new challenging deployment scenarios for multimedia streaming in wired-wireless integrated networks. Streaming services should consider not only the support of different forms of mobility and connectivity, but also runtime service personalization based on client characteristics and location, while possibly maintaining streaming continuity independently of client roaming. The paper proposes an original middleware solution based on mobile proxies that work at the wired-wireless network edges, close to their limited wireless clients, to support their personalized access to continuous services, especially by pre-fetching multimedia contents to avoid streaming interruptions. In particular, the paper focuses on how to exploit handover prediction i) to migrate mobile proxies in advance to the wireless cells where mobile clients are going to reconnect, and ii) to proactively manage mobile proxy buffers, thus reducing memory and bandwidth usage. Experimental results show that our original lightweight solution for IEEE 802.11 cell handover prediction can significantly improve the management of proactive multimedia buffers, by respecting the challenging time constraints of the addressed application domain.