Shutter speed should be set at YOUR FRAME RATE times 2
23.98 FPS would be Shutter Speed of 1/50
NOTE: Black Magic Pocket can set shutter speed OR shutter angle choose shutter speed as it is clearer to measure.
The difference between shutter speed and shutter angle is how they are measured. Shutter speed is measured in fractions of a second. At this angle, the shutter speed is half the frame rate. For a film shot at 24 fps, the standard shutter angle is 180 degrees.
MORE ON SHUTTER SPEED
Here is the following link and explanation from VIDEO MODE:
For example, when shooting at 25fps, your shutter speed should be 1/50 of a second. If your camera can shoot at 50 or 60 fps, your shutter speed should be 1/100 or 1/125 of a second. The reason for this 180-degree rule is because it helps us to record video that contains natural movement. If the shutter speed is too slow, you’ll get blurred movement, if you shoot at a shutter speed that’s too high, everyone in your scene will look like robots or as if they were recorded in stop motion. Sticking to the 180-rule will give you the most natural movement.
LINK: http://www.thevideomode.com/tuition/how-shutter-speeds-work-when-shooting-video-263/