Archived Kimimaru4000 video from YouTube. Original description mostly intact:

I haven't found a video for this so I decided to upload one. This shows dialogue for the Zora's River Kaepora Gaebora in The Legend of Zelda: Ocarina of Time that is unused in a normal playthrough.

The conditions are outlined on TCRF (https://tcrf.net/The_Legend_of_Zelda:_Ocarina_of_Time/Unused_Text#Zora.27s_River). Kaepora Gaebora spawns in Zora's River once you obtain Zelda's Letter, but he won't say this dialogue unless you learn Saria's Song before Zelda's Lullaby. Additionally, Saria appears in the Sacred Forest Meadow to teach you Saria's Song after obtaining Zelda's Letter. Therefore, you must get the letter from Zelda and leave the Castle Courtyard without learning Zelda's Lullaby.

There are a couple of reasons this is impossible under normal circumstances. First, if you save and quit in the Castle Courtyard, you will load back into Link's House with the Pocket Cucco and the game will act as if you hadn't visited Zelda. Second, the cutscene for learning Zelda's Lullaby extends extremely high and far to the sides, if not infinitely, so trying to get above, below, or around Impa will put you in the cutscene and teach you Zelda's Lullaby.

By obtaining a warp song early and having Bottled Bugs or a Fish, you can warp out of the Castle Courtyard with Ocarina Items, since you can't use the ocarina in there, after receiving Zelda's Letter. One way of getting a warp song is to enter Gerudo's Fortress as a child and make your way to the Spirit Temple where you'll learn the Requiem of Spirit. Once you've obtained the letter, warp to the Desert Colossus and make your way back through Gerudo Desert and hover over the gate. From there you can learn Saria's Song and head over to Zora's River to see Kaepora Gaebora say this text.

Thanks for watching and enjoy!