The advent of 5G networks offers a new challenge for mobile network operators, namely the more efficient delivery of multimedia services. With this in mind, the EU-funded OPTIMIST project aims to develop a modular end-to-end service platform that will offer optimized delivery of personalized video content in 5G mobile networks. It will achieve this by designing and implementing various multi-access-edge-computing (MEC) services as virtual network functions (VNFs). The VNFs will be instantiated and optimised on the fly to construct a video service chain that meets the personalised requirements of 5G mobile video consumers. The project will provide one of the first worldwide implementations of MEC-enabled service provisioning in 5G networks that is fully compatible with the emerging global reference architectures.