Motion Picture Assn. of America prexy-CEO Jack Valenti will discuss copyrights, ratings, the Hollywood strike threat and other issues affecting the business today as Variety.com hosts its first Big Talk live discussion.The moderated event will start at noon PDT. Site visitors can submit questions in advance or during the talk. Since 1966, Valenti has served as the voice of the motion picture industry, especially on Capitol Hill. This open forum represents an opportunity for industryites and the public to ask him questions directly.