Primarily, smooth streaming allows for the use of multiple video quality feeds from the same resource as they relate to available bandwidth. So if a user has a 1 megabit line, they will get a lower quality feed than a person with a 10 megabit line. Also, it will account for fluctuations. So lets say the person with the 10 megabit line has some network issues. Instead of the video stopping, it will go to lower quality then back to higher quality as his connection quality changes. Sites like Netflix use this.
