Here is the press release with details.
Secretary Clinton To Participate in a Conversation on the Obama Administration's National Security Strategy at the Brookings Institution on May 27
Office of the SpokesmanWashington, DC
May 25, 2010Secretary of State Hillary Rodham Clinton will participate in a conversation with Brookings Institution President Strobe Talbott at Brookings on Thursday, May 27 at 1:30 p.m. They will discuss the major points of the Obama Administration’s National Security Strategy (NSS), including preventing nuclear proliferation, terrorism and al Qaeda, use of military force, development and diplomacy. Secretary Clinton will take questions from the audience.
No mention of a webcast, though. I will look for the video.