I just want to add to this. When laying down, your neck movement range is a little more limited. So, everything has to be within that range of movement, or its uncomfortable to look at lists, and its uncomfortable to navigate around and use controls. In photography, you have the rule of 1/3's.. Which basically shows you where to focus on to make your subject and background/foregrand in the correct balance to be a good shot. The idea is, if you draw a 3x3 grid on the screen, you always want to focus your subject at the 1/3 x 1/3 intersection of the screen to line them up properly in the shot. In THIS case (for vr videos), you want to take the center square, of that 3x3 grid, redraw another 3x3 grid in that center square, and consider that your area of positioning. I have done A LOT of experimentation with converting standard 2D to 180 degree VR videos, and this is something I have learned through experimentation. If your video is 3840x1920, then your 3x3 grid should fit within an area, in the center, that is 1280x640...everything that you want people to focus on and navigate to or control has to be within that area.
