Film cameras allow you to change the shutter speed, which allows you to use it for exposure control, and to change the motion blur of fast moving objects. Video cameras don't have a mechanical shutter, but CCD image sensors can have a similar electronic function, controlling the scanning and discharging of the device.
The basic premise is that if the sensor can only register an image for a very quick moment in time, any high speed movement will be captured as a still image. However, a lot of light will need to be received. With the converse being that the more time it can register an image, more light will be received, but fast motion will be blurred.
Being able to take out the blur is particularly desireable when slow motion playback will be used, as you want to see clear still images of each frame. However, for normal playback, the pictures will seem more jerky, and it's usually more desirable to have some motion blur in the picture, to smooth them out. So, generally, you only use the SES for special shots.
Still cameras can take shots in very low light by exposing the frame for a very long time, but this isn't practical for most video cameras. If you were shooting a still image, such as a product shot, you could do that. But if you were filming anything that moves, such as people, they'd become a smudge. The slowest you can run video exposure at is the same as the video frame rate, 25 or 30 frames per second (depending on your local television standard). Though the usual slowest rate is the video field rate, or 50 or 60 fields per second (again, dependent on your local television standard). Using the frame rate can be a technique to get a “film look” out of video, since film is 24 frames per second, you get closer to film's motion blur by shooting at similar speed.