I suspect that the red numbers are actually LED's that flash so fast that you can't detect it. I thought of this when I noticed LED screens seem to stretch the image when looking from one side of it to another. I have an alarm clock with green numbers, and that happens on occasion.

Also, there are devices to "write" words in midair. It only uses a single bar of LED's. You hold a handle, spin the device (like a helicopter...), and when you go fast enough, you can see a word clearly. Yet, when this device is stationary, it is really difficult to tell if an LED is flashing or not.

What I think is happening is that your brain is fixing what it perceives as stationary, solid objects into a single image, so it does not move. The LED's, on the other hand, flash while the vibrator is in mid-stroke (or rotation... whatever.) just as the brain is getting a new image, so the number appears to move.

I am no engineer or doctor, but this might be how it actually works...