5G multicast/broadcast multimedia service (MBMS) can efficiently transmit multimedia data for a large number of mobile users simultaneously over broadcast or multicast channels of the mobile network. This paper investigates the ability to provide full-duplex (FD) relay for 5G MBMS using Unmanned Aerial Vehicles (UAVs). To increase the multimedia data transmission rate, the coordinated multiple point (CoMP) technique is used to aggregate data from multiple base stations via UAV relay. Also, to improve transmission reliability, Raptor Q, an advanced fountain code, is used to encode messages in the application layer. Based on these two technologies, a 5G MBMS technical solution based on UAV full-duplex relay is developed. Through the simulation of the system error block rate under various scenarios, it is shown that the proposed scheme can significantly improve the transmission performance of 5G MBMS traffic under different numbers of participating base stations, different UAV flight heights and different flight trajectories.