Identification of sugar

Benedict's solution is used to identify the presence of sugar in food.

To test for sugar, place a few drops of Benedict's solution in a test tube along with the food to be tested. Heat the mixture over a Bunsen burner. If sugar is present the colour of the solution turns orange.

Lemonade is tested for the presence of sugar.

The mixture of lemonade and Benedict's solution is heated until it turns orange in colour.

What does this indicate?
Would the mixture turn orange if Diet lemonade was used instead? Explain.
A particular brand of orange juice is described as having no added sugar. A sample of this orange juice is tested for sugar. Click to see a 120kb video of the results. Explain the results.