SuperView is a new feature introduced with HERO3+ Black Edition which allows you to capture an immersive wide angle perspective. What this mode does is it takes a 4:3 aspect ratio and dynamically stretches it to a 16:9 aspect ratio. This can be a great choice because it uses the height of the camera's sensor that you get with 4:3 meaning that you will see more of the sky and ground assuming you are pointed at the horizon.
What does dynamic stretching mean?
The way it works is that the camera automatically stretches out the sides of the video to fit into the 16:9 frame. The center of the frame is unchanged, only the edges are adjusted.
When to use SuperView?
There are a ton of scenarios where SuperView would give great results. Activities where you have the camera mounted on your head and chest such as biking, skiing, motocross, etc. would all work great. Really anything without a lot of important focal items around the edges of the frame. So you may want to avoid using SuperView in situations where there are people are the edges of the frame since they will be stretched a bit.