@atpfm another way to try and resolve the 3D vs. immersive video comparison Casey was trying to make:
3D videos are like looking out an apartment window at the Macy's Thanksgiving Parade as the floats go by. It's 3D, but the viewport is fixed.
Immersive videos are like you stepped out onto the balcony to view the same thing. Your location is fixed, but you are free to move your head and what you are viewing all around you.