Data partitioning, one of the MPEG-4 video error resilience tools, enables better error robustness. However, it suffers from serious error propagation problem. In this paper, we use an experimental approach to model the error propagation with several commonly used error detection conditions. It is shown that errors detected in forward section of texture data may be propagated from motion data, while those in DCT coefficients mostly result from themselves. Furthermore, the motion marker is the major error source for several error conditions detected in motion part. According to these characteristics, motion marker assumption and backtracking-based concealment strategies are proposed to achieve more accurate error localization in bitstream domain.