I need to talk about this a bit to see if I understand what's happening.
There are two things going on related to subject motion.
One is that the shutter speed (length of time the shutter exposes the sensor for each frame) controlling exposure. So at 1/60 sec shutter speed, the sensor is being exposed for each frame for 1/60 second.
But also the shutter is chopping the motion of the subject into discreet segments with gaps in the total motion.
So at, say, 30 fps, a second of continuous motion is chopped into 30 segments. But each segment is only 1/60 second, so I've actually only captured a half second of that second of continuous motion in 30 segments with 1/60 of a second of gap between each 1/60 second of capture. At the same time, that 1/60 shutter speed is allowing a certain amount of motion blur in each frame.
If I increase the shutter speed to 1/125 of a second and keep the frame rate at 30fps (opening the aperture or increasing ISO to compensate exposure), then I've only captured 1/4th second out of that second of motion--there is a twice as much gap in the motion from frame to frame. From one frame to the next, I'm missing twice as much motion with twice the shutter speed. But that faster shutter speed also cuts the amount of motion blur in half in each frame.
Thus, the video will look choppier at the faster shutter speed because not only am I losing more of the continuous motion, but each image is also sharper. As I raise the shutter speed more, the eye begins to discern each frame as a separate image because it is sharper with more gap in the continuous motion before the next frame.
Now, my question here regards metering. Up until now, I've been using a still camera light meter. But I'm not sure what a cine meter--with an fps setting instead of a shutter speed setting--actually does for me with video. Does the cine meter presume a fixed relationship between shutter speed and fps that exists with a film camera but not with video?