Liam Hemsworth is the youngest of the famous Hemsworth brothers, best known for starring with Jennifer Lawrence in “The Hunger Games” movies and for his recent marriage to Miley Cyrus. In this week’s “Sunday Sitdown,” Willie Geist chats with the Australian actor about the legendary brother fights in his household growing up, and later fighting his brother Chris for the role of “Thor.” Liam also discusses trying his hand at comedy in the new movie “Isn’t it Romantic.”