This paper addresses the problem of distortion modeling for video transmission over burst-loss channels characterized by a finite state Markov chain. A Distortion Trellis model is pro- posed, enabling us to estimate at the frame level the expected mean-square error (MSE) distortion caused by Markov-model bursty packet losses. A sliding window algorithm is devel- oped to perform the MSE estimation with low complexity. Simulation results show that the proposed models are accu- rate for all tested average loss rates and average burst lengths.