Participation as of actor, film editor has what average year?
CREATE TABLE "other_film_projects" (
  "year" real,
  "english_title" text,
  "original_title" text,
  "country" text,
  "length" text,
  "participation_as" text
);
SELECT AVG("year") FROM "other_film_projects" WHERE "participation_as"='actor, film editor';