Normally you double the shutter speed compared to the frame rate to include a motion blur that looks good. But if you then apply stabilisation post processing, you end up with a shot that has motion blur yet isn’t moving. So you want to set a very fast shutter speed, and then you might introduce fake motion blur in post processing later that matches the movement of the stabilised video.
Interesting—and makes sense. (Perhaps motion blue becomes a post-process as well then, ha ha.)
Kind of a tangent: One of the remarkable things to me about the "Dykstra flex" cameras developed for Star Wars was that the dolly/stepper-motors moved the camera while the shutter was open giving those fly-by shots full motion blur. Freeze any frame where there is a space battle and it is obvious.
That small detail was not small at all in selling the effects of the film.
But one of the effects guys joked that some team had borrowed the camera for some effects they were doing for a TV show or film—and they used Dykstra-flex in sort of a "stop motion" manner. He was dumbfounded why someone would move the camera, pause to expose a frame, move again to the next location, pause to expose. Just walking away, leaving motion-blur on the table…
This is one of those things that pops up on fixed aperture cameras where the only way to control the exposure is with shutter speed. We used this when using GoPros in the early days of live action VR. We'd also run at 60fps. Any kind of motion blur would just become problematic when trying to stitch the footage together especially since the cameras were catching objects in different parts of the wide angle lenses.
ND filers slow down the shutter speed which will only increase the motion blur. When shooting in the sunny outdoors, you're going to be using the lowest ISO. The only thing left to control the exposure is the shutter speed. So with a fast shutter and 60fps also decreasing the exposure time the motion blur is going to be reduced as much as one can get.
If you're on the lowest iso you could use an ND filter and bump the ISO a little higher giving some room to move up and down the ISO values to match the conditions while keeping the shutter speed fixed. That's kind of the primary function of an ND filter.
For video ideally you want both the shutter speed and aperture fixed since having the depth of field fluctuate in the video isn't ideal either.
Yes. It's confusing, which is why this is often discussed in terms of shutter angle, which makes this a litter easier to understand: https://www.youtube.com/watch?v=ehpdzt0JHUc