Ultra-High-Definition (UHD) video applications such as streaming are envisioned as a main driver for the emerging Fifth Generation (5G) mobile networks being developed worldwide. This paper focuses on addressing a major technical challenge in meeting UHD users’ growing expectation for continuous high-quality video delivery in 5G hotspots where congestion is commonplace to occur. A novel 5G-UHD framework is proposed towards achieving adaptive video streaming in this demanding scenario to pave the way for self-optimisation oriented 5G UHD streaming. The architectural design and the video stream optimisation mechanism are described, and the system is prototyped based on a realistic virtualised 5G testbed. Empirical experiments validate the design of the framework and yield a set of insightful performance evaluation results.