Playback Latency Reduction for Internet Live Video Services in CDN-P2P Hybrid Architecture Since Internet live video services provide media streaming over unmanaged networks, service cost and QoS (Quality-of-Service) are important factors for commercial deployment. For this open Internet content delivery, the CDN-P2P (Content Delivery Network-Peer-to-Peer) hybrid architecture can be an appropriate solution in terms of scalability and cost. In this live streaming system, lots of P2P (Peer-to-Peer) keeps the random unstructured graph for data delivery resilience even with node join and leave dynamics. However, since a node pulls required data from nearby peers in the unstructured overlay due to delivery graph elasticity, pull-based unstructured P2P live streaming services experience significant playback latency. In this paper, we propose a playback latency reduction method by limiting the radius of unstructured P2P in CDN-P2P hybrid architecture. Especially, we formulate this architecture as a BDMRST (Bounded-degree Minimum-radius Spanning Tree) problem and propose a distributed solution with slight modification of the gossip-based membership protocol. We also evaluate our proposed method with simulations.