That's also because of the 'shutter speed' or 'shutter angle'. Basically each frame stays 'open' for a certain amount of time to let the light in. Anything slower than say 1/500s is going to introduce motion blur into the frame.

Shutter Speed/Angle are also creative choices. Anything that is faster than 1/50th (180 degree shutter angle) will introduce a 'staccato' effect to the video. Anything slower will be mushy/blurry.

Somewhat off topic, but interesting nontheless!