The popular video-sharing YouTube site, which is being purchased by Google for $1.65 billion, limited access to a political ad that mocks the Clinton administration's policy on North Korea, but contains no profanity, nudity or other factors generally thought objectionable. The company announced a "flagging" policy change just this week, about the time that a controversial spoof by Republican filmmaker David Zucker depicting former Secretary of State Madeline Albright as a cheerleader for Islamic terrorists started appearing with a warning page in front, requiring verification that a viewer is 18 before the video will appear. The short film by Zucker,...