One viewer revealed that he searched for his biological father -- akin to Randall's journey -- while watching the show. Another connected with Rebecca's demons and fears, and shared that it opened his eyes to what his mother went through. Several spoke of the powerful impact of the heart-wrenching scene when Randall's dad, William, died, saying it brought them back to their own loss.
What they didn't know was that Mandy Moore, Milo Ventimiglia, Sterling K. Brown and Chrissy Metz were just on the other side of the curtain, watching them reacting to poignant moments from the first season of This Is Us and tearing up themselves.
You have to watch the video below to see for yourself: