Are there advantages of 3D graphics and HD video if I am not using my computer for those purposes? My work is mostly text based (and audio). The 3D environment of Ubuntu Desktop is uncomfortable for my eyes but it seems to be an integral component of Ubuntu/Unity.
SnapOverflow
No there really are not advantages unless you want to have fancy desktop effects like the cube as shown here, your computer will use a lot less resources with 3d effects turned off.
HD video is just a better quality picture for the pleasure of your viewing but if you do not care about better picture quality then there is no advantage to HD video, it is actually hard to tell the difference on my monitor between the two.