1. A virtual broadcast server adapted to concurrently route each of a plurality of segments of digital content to a plurality of client nodes of an underlying network for concurrent playback of the segment by the plurality of client nodes, the virtual broadcast server comprising: (a) an overlay network database adapted to store a network topology representing a current state of an overlay network built on top of the underlying network, wherein the network topology of the overlay network includes: (i) each of the plurality of client nodes, each client node being a node of both the overlay network and the underlying network, and each client node being a destination client node adapted to receive the segment for concurrent playback of the segment by the plurality of client nodes, and (ii) a set of routing paths each segment traverses as it is relayed among the plurality of client nodes to facilitate concurrent playback of the segment by all destination client nodes, wherein (A) a subset of the client nodes are source client nodes, in addition to being destination client nodes, adapted to relay the segment to one or more of the destination client nodes, and (B) each routing path defines a pair of source and destination client nodes; (b) a performance tracker adapted to monitor metrics from network traffic among the plurality of client nodes along the overlay network; (c) a learning engine adapted to: (i) maintain: (A) an ASN interconnection map of the underlying network, including a plurality of ASNs interconnected by a plurality of ASN peering points, and (B) an ASN location of each client node, wherein the ASN location identifies the ASN in which that client node is located; and (ii) continuously quantify congestion levels at the ASN peering points, based upon an analysis of the metrics, the ASN interconnection map and the ASN location of each client node, wherein the congestion levels change as network traffic across the ASN peering points ebbs and flows; and (d) an overlay network creator adapted to dynamically reconfigure the network topology of the overlay network based at least in part upon changes in the quantified congestion levels, by modifying the set of routing paths.