If the amount of U.S. viewers is 2.05 milliom, who was the episode directed by?
CREATE TABLE "table1_23399481_2" (
  "series_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "u_s_viewers_in_millions" text
);
SELECT "directed_by" FROM "table1_23399481_2" WHERE "u_s_viewers_in_millions"='2.05';