VIDEO : Sienna Miller Thanks Ben Affleck For Believing In Her

Sienna Miller has made a name for herself in the acting community but the 'Live By Night' actress is not taking all the credit. In fact, she's giving a great deal of it to fellow actor Ben Affleck. Affleck cast Miller in his new gangster film 'Live By Night' to which Miller is so grateful for. "He's always been a vocal supporter of mine as an actor," Miller says adding, "and [he] felt like I hadn't had the opportunities I deserved."