I found this song through a twitter post about a yet to be released singing Izzy toy linked in an Equestria Daily article and noticed a suggestion in the comments. Eeyup, it syncs!

I would guess that this scene is within Izzy's home given the arts and crafts supplies, and that perhaps the goal is disguise everypony as unicorns to "Fit Right In" in Bridlewood.

Can't wait for the movie! I NEED that plushie!

Also tried my best to transcribe the lyrics, but there's a couple parts that are hard to make out :(

Yes, I really went out of my way to sync like one second of video to the song.