Rolling shutter is a distortion your video, where objects tend to look slanted when you move your camera quickly. Not to get to technical, but it has to do with how fast the camera can get the information from the sensor to the processor. Cameras will read the sensor bottom to top, so if an object is changing quicker than the camera can process the image, this can make the object come out distorted. For example, common test camera reviewers use to measure rolling shutter issues is to film a telephone pole out of a moving car. The more slanted the telephone poles look, the worse the rolling shutter.

Now the a6300 has very bad rolling shutter. Panning the camera quickly will cause the scene to take on an almost jello effect. This is not an issue if you do not move the camera too fast, but that depends on your needs.

Check out this link for more info.
https://www.youtube.com/watch?v=bQU1Jylk3jQ