Wyner-Ziv video coding (WZVC) has gained considerable interests in the research community. In this paper, we present a model to examine the WZVC performance and compare it with conventional motion-compensated prediction (MCP) based video coding. Theoretical results show that although WZVC can achieve as much as 6-dB gain over conventional video coding without motion search, it still falls 6 dB or more behind current best MCP-based INTER-frame video coding. We further study the use of subpixel and multireference motion search methods to improve WZVC efficiency. The analytical results are confirmed by simulations and experiments.