Joint source-channel coding schemes have been proven to be effective ways for reliable multimedia communications. In this paper, a joint source-channel decoding (JSCD) scheme that combines the hidden Markov source (HMS) estimation and low-density parity-check (LDPC) coding is proposed for the standard MPEG-2 video transmission. The LDPC code of the proposed scheme has a near-Shannon-limit error-correcting capability, while the HMS estimator may accurately extract the residual redundancy within the MPEG-2 video stream without any prior information. Furthermore, with a joint iterative decoding algorithm, the estimated source redundancy may be well exploited by the LDPC decoder, and the channel decoding feedback may refine the subsequence HMS estimation, thereby effectively improving the system performance. On the other hand, we also show that the proposed JSCD scheme has approximately the same computation complexity as that of the standard decoding scheme. Moreover, it is worth noting that the proposed scheme is based on separation encoding schemes, which is very convenient to be applied to existing multimedia transmission systems.