On August 27, musician/actor extraordinaire FKA twigs debuted her new music video on the surreal FX comedy anthology show Cake. An unorthodox place to debut a music video, to be sure. But I am telling you: This visual, for her single "Sad Day," deserves its place on the small screen and more. Directed by FX and music video wunderkind Hiro Murai (Atlanta, "This Is America"), "Sad Day" is a surreal, inventive, and psychologically exacting look at love, obsession, and ennui — oh, and it also happens to involve a straight-up wushu sword fight. Yep! FKA twigs literally does battle …