Scary thing, this one…
DepthBlur works fine, but MotionDepthBlur, when the rendering, eats up one thread (which seems low) but ALL of the available memory. This causes both of my workstations to crash (8GB and 32GB). I’m loathe to test this on coworkers machines, since we’re encroaching on a deadline now.
Though it was a bit odd how it interpreted red/green. It had them backward, so it was making an orthogonal blur. Fortunately there are controls to set the scaling for X and Y separately.