It's sweet, but it's also a little bit sad.
Gawker points us to this bit of human emotion making the rounds on the Internet today:
If you, like us, don't recognize the song, it's Say Something sung by A Great Big World and Christina Aguilera. If we were asked to decipher the somewhat cryptic lyrics, we'd say this is a song about lovers finally letting go of something that was once really good.
In any case, the toddler's dad says on YouTube that this captures the first moment his 4-year-old son has been "moved" by a piece of music.