[Philip Lelyveld comment: Canon showed this system at CES 2017. It is not live video. They use video to construct a 3D model that you can freely navigate through after it is constructed.]
The Free Viewpoint Video System utilizes existing imaging technologies that Canon has developed over the years. The company explains that stadiums utilizing this system will have multiple high-res cameras positioned around the arena; these cameras record the action simultaneously, while image processing technology rehashes that footage as high-resolution 3D spatial data.
The end result is an immersive video in which users are able to move a virtual camera within this rendered 3D space, providing a view of the action from various viewpoints and angles around the field.