Just a theory, but when you take a photo, your hands have to be still for the shot, when you press it, hardware OIS kicks in and in a very short time period of when you press that button to take the picture, the camera's hardware compensates by staying still.
If you were recording a video, the amount of battery life that would be consumed from the device having to shift/move the camera would cause the battery to drain much faster than any lights, screen, etc. so it wouldnt be practical to use a hardware OIS for video capture.
If you were recording a video, the amount of battery life that would be consumed from the device having to shift/move the camera would cause the battery to drain much faster than any lights, screen, etc. so it wouldnt be practical to use a hardware OIS for video capture.