1. A virtual broadcast system for routing digital content concurrently among client nodes of an underlying network, wherein shared links interconnecting components of the underlying network have a frequently changing congestion level as network traffic across those links ebbs and flows, the virtual broadcast system comprising: (a) a memory storing a map of the components and shared links interconnecting them, including a location of each client node within one of the components; (b) a performance monitor that generates metrics from network traffic among the client nodes that crosses those shared links along an overlay network built on top of the underlying network; (c) a deep learning engine that analyzes the metrics and the map over time, and forecasts congestion levels reflecting the changing capacity of the shared links over time; and (d) an overlay network creator that generates, based upon the forecasted congestion levels, an overlay network topology including an optimal route among the client nodes along the overlay network.