Spoiler Alert! At a special screening of the season finale of "This Is Us," Mandy Moore and Milo Ventimiglia tell Access Hollywood's Alex Hudgens about diving into the tough scenes between Jack and Rebecca in the show's Season 1 finale. And, the two reveal which of their castmates came to watch them film those moments.Visit us at http://www.AccessHollywood.com/Connect with Access Hollywood:Facebook: https://www.facebook.com/AccessHollywoodTwitter: @accesshollywood (https://twitter.com/accesshollywood)Instagram: AccessHollywood (http://instagram.com/accesshollywood) Snapchat: OfficialAccess