Metamaterials offer exotic electromagnetic possibilities, beyond those usually associated with conventional materials. Two general phenomenons associated with metamaterials have attracted much recent attention: negative-phase-velocity (NPV) propagation, and cloaking and invisibility. Relatively simple materials may (i) support NPV propagation, and (ii) offer concealment to a substantial degree, by means of translation at constant velocity. By virtue of the Minkowski constitutive relations, planewave propagation in a homogeneous, instantaneously responding, dielectric-magnetic material that is isotropic in the co-moving reference frame, can be classified as positive-, negative-, and orthogonal-phase-velocity (PPV, NPV, and OPV) propagation in a non-co-moving reference frame, depending upon the magnitude and direction of that reference frame's velocity relative to the material. The perceived lateral position of a transmitted beam, upon propagating at an oblique angle through a slab of homogeneous, instantaneously responding, isotropic, dielectric material, can be controlled via the velocity of the slab. Therefore, by appropriate choice of the slab's velocity, the transmitted beam can emerge from the slab with no lateral shift in position, and a substantial degree of concealment may be achieved.