An efficient video dehazing system based on the dark channel prior (DCP) is proposed. For the proposed system, the original DCP-based dehazing method is modified in order to achieve a fast execution of the airlight estimation without noticeable degradation of the dehazing quality. The proposed system is implemented in a heterogeneous multi-processor system-on-chip, for which the overall dehazing process is described in OpenCL and synthesized into the custom circuitry targeting an FPGA. In average, the execution time of the overall dehazing is reduced by 41.3% by the fast execution of the airlight estimation when compared to that of the system based on the original method while the dehazing quality is maintained.