Based on chapter two of
ís fanfic, Book Air [link]
in which Korra goes back to the past to deal with Noatak. The figure in the sky is Korra and she's falling really fast (because of time traveling).
I really like this fic. This is how Korra should have gotten her bending back, not backed-up on an external spiritual harddrive or something... And it has Noatak too, which is good.
Korra, Noatak (c) Bryke
soundtrack: mystical Yoko Kanno stuff