Confidence Interval graph explained

Did you ever wonder what those curved "confidence interval" lines mean, above and below a regression line, in a graph? Dr. Gerard Verschuuren explains it in this two minute video (posted with his permission).

This video is the first two minutes of a ten minute video, which also explains how to calculate them, in Excel:

(Downloaded with Youtube Video Downloader, edited with Windows Movie Maker, and converted with Handbrake.)