Earthbound, like Ocarina of Time, is a game about collecting melodies. Unlike Ocarina, where each song has its own unique purpose, Earthbound's Eight Melodies combine together to form a single song--one that is meant to save the world.
The video above includes an arranged version of those Eight Melodies. It's called Smiles and Tears, and I can't think of a better way to describe it. This song is the final punctuation on a childhood adventure, accompanied by music ranging from silly to strange, kooky to creepy, mysterious to maddening.
And if I can make an unrelated remark: you owe it to yourself to play Earthbound in any way that you can.