One major problem in Wyner-Ziv video coding with unsupervised motion vector learning is one the quality of blockwise motion estimator. nearest neighbor interpolation of block -wise motion vector field onto pixelwise motion vector field in fact creates step-like transitions at block boundaries. the actual pixelwise motion vector field has smooth transitions across space. this paper proposes method of bilinear interpolation to improve pixelwise motion vector field which mitigates the boundary effets. the implementation of this method in WZ video codec with unsupervised motion vector learning has led to 3-4 % and 6-7% bit rate saving for GOP 2 and 8 respectively, when compare to nearest-neighbor interpolation method. rate-distortion performance improved to 0.46 dB and 0.27 db for GOP 2 and 8 respectively.