Nowadays, distributed source coding (DSC) and distributed video coding (DVC) have been receiving more and more attention due to the distinct contributions to the easy encoding. At the same time, with more new requirements coming forth in the current network communication, the scalability of bit stream has been a new focus in the real applications. A scalable DVC scheme is presented without requiring layered coding in which the main attributions of DVC, namely the capabilities of easy encoding and robustness, are inherited remarkably and the property of scalability is also integrated simultaneously. Based on the block Slepian-Wolf set partitioning in hierarchical trees (SW-SPIHT), the Wyner-Ziv frames are encoded to get the scalable bit stream. In addition, the binary motion searching is explored at the decoder with the help of a rate-variable 'hash' from the encoder to improve the performance of the whole system. The final experimental results show that our system has higher peak signal-to-noise ratio (PSNR) than the pixel-domain DVC at the high bit rate. What is more, the scalability in signal-to-noise ratio (SNR) is also achieved satisfactorily.