This paper proposes an efficient data representation scheme to improve the performance of a data hiding method [1] in MPEG compressed domain. Even though [1] completely preserves the quality of the modified video to that of the original (compressed) video and [1] is reversible, [1] suffers from consistent filesize increase caused by data embedding. To suppress filesize increase, reverse zerorun length (RZL) is proposed to efficiently encode the message. RZL utilizes the statistics of the macroblocks with respect to [1], and the distance between two excited macroblocks is considered to encode a message segment. RZL simultaneously achieves high payload and high embedding efficiency, thus RZL is able to suppress the filesize increase caused by data embedding. We theoretically analyzed that RZL outperformsmatrix encoding for both payload and embedding efficiency for this particular data hiding method. Experiments are also carried out to verify the theoretically deduced results, and the observed results agree with the expected outcomes.