Kit Harington speaks with Insider's Kirsten Acuna about filming one of "Eternals" two top secret post-credit scenes, why it's a strong ending to the movie, and his hopes to return in another Marvel film. Harington shares that he has read up on who his character could become, but he doesn't know anything else at this point. He hasn't tried on a helmet or costume or anything in relation to who his character could become.