I think it means that, given a normal flat 2D video, you get back that video but as a 3D scene, meaning you can move and pan the camera around as the 3d video p

I think it means that, given a normal flat 2D video, you get back that video but as a 3D scene, meaning you can move and pan the camera around as the 3d video plays. And I guess they call it 4D since you had a flat 2d video + time dimension, so 3d video + time dimension = 4 dimensions.