This sort of thing is rather outside the normal range of content submitted to TILES but sure, why not? Seems fun? TILES approves it as an alien cultural artifact.

Some debate ensues as to what color the dress is. Perhaps the somewhat poor/overcompressed quality of the video is intentional in order to produce this illusion?

A few children who watch the music video ask their parents why everyone is ignoring Yanny, the lonely girl who wears a black and blue dress. 

The parents... mostly don't see it? The song's about a girl named Laurel who wears white and gold, isn't it?

One parent remembers that a review he'd scrolled past earlier mentioned seeing the dress as black and blue, and there was a bit of a debate in the comments. If he squints at the video a bit, he can kind of see where that's coming from -- it seems very likely off given that the title of the song is The Girl In The White and Gold Dress, but maybe his daughter is onto something that the reviewer from earlier noticed too? What's this 'Yanny' thing, though?

His daughter says Yanny is the girl in the cold who no one pays attention to. Everyone pays attention to her sister Laurel but Yanny is left lonely to dance by herself, in her black and blue dress. Why won't he hear Yanny?  

The father is naturally a bit disturbed by this. He strains to hear what his daughter is describing, but it just doesn't seem to be there -- he can see the dress thing, but the lyrics elude him. He calls his wife over to see what she hears and sees (neither he nor his daughter tell her what to expect, of course, so as not to ruin the experiment). She puts on a pair of headphones and cues up the video...

...and she also hears a fun, happy song about a girl named Laurel spinning in the sun in her white and gold dress. Their daughter is insistent that there's something there, though! Like her husband, the mother can see the "blue and black dress" part if she focuses on it, but it very much wouldn't be her default assumption.

The father really doesn't hear these lyrics, but he is growing increasingly disturbed by his daughter's reaction. He decides that he'll write a review describing his daughter's experience and asking whether any others watching the video have experienced something similar.

A few parents reply saying they had similar experiences with their children hearing a song about Yanny, often being upset by how their parents 'ignored' Yanny.

The father is half-relieved, half-alarmed to see this. On the one hand, his daughter isn't insane or possessed or anything! On the other hand, a bunch of other families are having the same disturbing/upsetting reaction to this situation that he is -- there seems to be something weird or subversive going on here! He reports the video for further investigation as potentially dangerous, appending his daughter's transcription of the lyrics. It seems like she is hearing a totally different version of the song from the version audible to her parents, and when they get back from fencing practice her older brothers can't hear what she's hearing either.

The lyrics his daughter repeats are unsettling. The chorus is Yanny singing of how few see her and even fewer hear her. During the verses she sings of how she has to dance in the cold alone, of how her sister Laurel soaks up warmth and attention while Yanny shivers next to her unnoticed. At the end her young voice dips lower, low enough that the father might just barely be able to make out what his daughter hears, as Yanny begs for the listener to stop ignoring her too. 

The father listens again and really tries to make out these lyrics... and he can't. Yanny just isn't there for him. It's deeply frustrating, knowing something is disturbing your child but not being able to see it, and doubly so because she has such a clear understanding of what it is. When a baby cries for no discernible reason that's one thing, but when your daughter is able to very distinctly explain what a song is about and even tell you the lyrics and there's just no reflection of what she's saying at all when you listen yourself, that's an altogether different and much creepier experience.

The youngest of her brothers, a teen, thinks he can make out some of the end part maybe, but even for him it's indistinct? The parents get the daughter to write down the lyrics she hears alongside the lyrics they hear (fun and cheerful words about dancing in the sun in summer!); they submit the two sets of lyrics as part of a content report to TILES.

The Girl In The White and Gold Dress is quickly pulled from circulation. Further analysis finds that the song has additional elements overlaid on top of its normal vocals at quite high frequencies that are only audible to a small minority of the population, almost entirely young children. To one who can hear those frequencies the "Yanny" version of the lyrics replaces the "Laurel" version, making the song quite disturbing -- the fact that most others cannot seem to hear this message only plays into the message itself. TILES is not amused. 

The Faylien envoys receives a message from TILES sharply questioning why one would find it appropriate to send such a thing -- not only is this creepy/disturbing horror content with no content warnings provided, but it seems designed in a way to target and disturb children in particular in a way that makes it hard for them to discuss the matter with their parents. While there's a certain ingenuity to the craftsmanship behind this that is in some ways appealing, it would never have been approved for general release to children without content warnings and a relevant note to parents if the hidden version of the lyrics had been understood.

All Faylien media distribution via TILES is suspended pending an in-depth evaluation, and those who have copies of Faylien media are warned that they should put it aside for the time being pending further evaluation.

The envoys are so sorry! Cleary this should have come with a notice of what it was. They'll add one to the start of the video, and a similar notice to any future work by this author they send over. 

Hopefully that fixes the issue? Oh also you have to admit the concept is pretty beautiful even if it's sad that people couldn't receive the warnings about it they wanted to receive. Beauty shouldn't come before happieness. 

Did... the envoys know that was what this was? Does anything else that's been submitted have little hidden surprises like this?

No, of course they didn't know! They can crowd-source checking over the songs with pitch-shifting to see if anything else stands out as having unmarked hidden messages like this? They'd be pretty surprised if they did though, usually Fayliens overtag their works, not under. 

Okay, that's good. The "you have to admit it's beautiful" reaction had us worried a bit.

(The TILES envoys agree that it is, in a sense, a very elegant and artistic work, making ingenious use of properties of the medium that would normally go unnoticed in order to convey a hidden meaning that reorients one's entire relationship to the work -- truly impressive! Unfortunately, that elegance and artistry was aimed at scaring children and creating misunderstanding and potentially distrust between them and their parents, an extremely ignoble goal.)

With that sorted Fayliens are excited to begin sending fiction again as soon as TILES is ready to receive it.

TILES is not altogether happy with how this progressed, but forgiveness is an important virtue. The Fayliens’ apology is accepted and interdimensional media exchange with the Fayliens will continue.

That said, increased scrutiny will be paid to future material both from this world and others, and TILES may update its procedures to provide increased scrutiny on such matters in the future. This ended up being relatively tame, but many are aware it could have been worse…