Super Mario Bros (NES) - The Ending
This is a video of the ending sequence of Super Mario Bros. on the NES
At the end of every world, a mushroom retainer (Toad) appears and tells you "Thanks for saving us Mario, but our princess is in another castle. When you defeat Bowser in World 8, The princess herself thanks you, and then tells you that you can select any stage to play in for fun now.
Here are some images from the Super Mario Bros ending sequence on the NES.