Australian-born actress Rose Byrne earned an Academy Award nomination for her powerful performance in the drama “If I Had Legs I’d Kick You,” playing a mother stretched to the limits. She talks with correspondent Tracy Smith about playing a woman losing all sense of control. Byrne also discusses her early years in Hollywood and the help she received from fellow Aussie Heath Ledger; and how she branched off from working in dramas like the TV series “Damages,” to comedies like “Bridesmaids.”