The increase in transmission errors poses a serious challenge to underwater acoustic (UWA) communication methods, especially with the real-time error-correcting transmission requirements for underwater videos. We propose a video transmission method that enhances efficiency by using target segmentation. By integrating the reliability of UWA channels with the structure of compressed video, this approach effectively combats the loss of crucial information. An enhanced YOLOv5 algorithm is proposed to partition video information flow into different importance levels, and orthogonal frequency-division multiplexing (OFDM) is employed for transmission. This allows video data assigned to higher importance levels to be transmitted over the low-frequency bands with lower attenuation, whereas less important data are transmitted over the high-frequency bands with higher attenuation. Simulation results demonstrate that our proposed underwater video transmission method significantly improves the peak signal-to-noise ratio compared with three baseline techniques in the signal-to-noise ratio range of 25 to 50.