We have previously proposed a P2P video broadcast method called MTcast for simultaneously delivering video to user peers with different quality requirements. In this paper, we design and implement a prototype system of MTcast and report the results of its performance evaluation in the real Internet environment. MTcast relies on each peer to transcode and forward video to other peers. We conducted experiments on 20 PlanetLab nodes, evaluated startup delay and recovery time from peer leaving/failure, and confirmed that MTcast achieves practical performance in a real environment.