I just noticed today that the Mesh Renderer component now has a checkbox called Motion Vectors. I don’t see this described in any manual so I’m wondering if someone could explain what this is supposed to be for.
EDIT: Nevermind. I finally found a thread about this here.
I believe the checkbox enables the mesh to be rendered into unity’s new motion vector buffer. Motion vectors track how much meshes and other things move from one frame to the next in screen space. The x and y movement is stored in a texture and shaders can now access that texture. It’s mainly used for updated image effects such as temporal antialiasing and motion blur.