Ellen celebrates Cinco de Mayo, and you're invited to the party. Check out what happens when Ellen is let loose on historic Olvera Street in Los Angeles and receives a lesson in Mexican culture. Joining Ellen for this celebration is ELLEN POMPEO from the hottest series on TV, "<b><i>Grey's Anatomy</b></i>." And, CRAIG FERGUSON ("<b><i>The Late Late Show with Graig Ferguson</b></i>") talks about his best selling book, "<i>Between the Bridge and the River</i>."