Underwater videography is like taking videos or movies, but the camera is put underwater!
You know how when you swim in a pool or at the beach and can see everything clearly but when you try to take a picture or video it's all blurry and distorted? That's because water changes how light moves, and cameras need light to work properly. So, special cameras and equipment are used to take good videos underwater.
The camera is usually placed in a waterproof case or housing to protect it from the water. This case has buttons and controls on the outside so the videographer can adjust the camera settings while underwater. Some videographers go really deep, like way down in the ocean where it's really dark, so they need special lights to brighten up the video.
When the video is done, it's taken out of the water and edited on a computer. The editor can add music, cut out parts they don't want, and make the colors look prettier.
People use underwater videography to make documentaries about sea creatures, to record scuba diving adventures, or to explore parts of the ocean that haven't been seen before. It's really cool to see all the different types of fish and animals that live underwater!