A video encoder/decoder and a video encoding/decoding method and medium. The video decoder includes a decoding unit which receives a video packet in which more significant items of items included in blocks of macroblocks, which make up the video packet, are arranged in a front part of the video packet and less significant items are arranged in a rear part of the video packet. The decoding unit sequentially decodes the items arranged in the video packet. Accordingly, an FGS encoding function is effectively performed without degrading the bit rate.