In this video he shows us a snowy scene where the background causes the image to be underexposed. Also, in this video he takes us to a dark background of trees that causes the image to be overexposed.
He reviews the standard types of metering in your camera. How to use those types of metering. Also, how do use exposure compensation instead.
Remember, it’s important you focus on the histogram instead of trusting your eye on the LCD. If you get in the habit of checking the histogram after every shot your images will always be properly exposed.