In the past few years, a number of practical video coding schemes following distributed source coding principles have emerged. One of the main goals of distributed video coding (DVC) is to enable a flexible distribution of the computational complexity between the encoder and the decoder, while approaching the coding efficiency of conventional closed-loop motion-compensated predictive codecs. In this paper we perform a rate-distortion analysis of a well-known Wyner-Ziv architecture, while focusing our attention on the impact of the motion modeling that is used for generating the side information at the decoder. Our analysis is structured according to a Kalman filtering problem and it allows us to compare three different scenarios: motion estimation at the encoder; motion interpolation at the decoder; and motion extrapolation at the decoder.