91-year-old husband serenades wife of 66 years and a 9-year-old uses jokes to help her sister

In this week's "Dear David," CBS News contributor David Begnaud shares two powerful stories of love: Jerome and Agnes Bourgeois of Houston, marking 66 years of marriage through song, and 9-year-old Nora Vaughn of Louisiana, spreading laughter to raise money for her sister with Rett syndrome.