AFAICT, neither Direct3D (d3d) nor OpenGL (opengl) are defaults for -video in the Windows OSD. The default is "auto", whatever that may be (OpenGL?). However, you can simply decide which one to use on the command line (-video d3d), or through mame.ini/mess.ini or a front-end.

A mind is like a parachute. It doesn't work unless it's open. [Frank Zappa]