NBC "Today" co-hosts Meredith Vieira and Matt Lauer address NBC's decision to air a video manifesto and photos sent to their network by Virginia Tech gunman Cho Seung-Hui. Victims' families canceled their appearance on the show this morning. RICHARD DREW | Associated Press   This video frame grab image taken from a video aired by NBC News yesterday shows the envelope that Virginia Tech gunman Cho Seung-Hui sent to NBC. AP Photo/NBC

NBC News was the recipient Wednesday of Cho's package of rambling, hate-filled video and written messages, with several pictures of him posing with a gun. Contents began airing on "Nightly News," and its rivals quickly used them, too.

Family members of victims canceled plans to appear on NBC's "Today" show Thursday because they "were very upset" with the network for showing the pictures, "Today" host Meredith Vieira said.

Virginia State Police Col. Steve Flaherty — who praised NBC Wednesday for coming to authorities first with the package — said Thursday he was disappointed with what the network showed.

"I just hate that a lot of people not used to seeing that type of image had to see it," he said.

NBC said the material was aired because it helped to answer the question of why Cho killed 32 people and himself on the Virginia Tech campus Monday.

"The decision to run this video was reached by virtually every news organization in the world, as evidenced by coverage on television, on Web sites and in newspapers," NBC said in a statement. "We have covered this story — and our unique role in it — with extreme sensitivity, underscored by our devoted efforts to remember and honor the victims and heroes of this tragic incident."

NBC and its MSNBC cable outlet will "severely limit" use of these pictures going forward, "Today" host Matt Lauer said, a restriction echoed by ABC News. At both CBS News and CNN, producers will need explicit approval from their bosses to use them going forward.

Fox News announced on the air late Thursday morning that it would no longer air Cho's material, saying "sometimes you change your mind."

These decisions, of course, came more than 12 hours after the pictures became available, after they already made their impact. The news cycle dictates they would be used less, anyway.

"It has value as breaking news," said ABC News spokesman Jeffrey Schneider, "but then becomes practically pornographic as it is just repeated ad nauseam."

Jon Klein, president of CNN U.S., said the decision to air it was a tough call.

"As breaking news, it's pertinent to our understanding of why this was done," he said. "Then, once the public has seen the material and digested it, then it's fair to say, 'How much should we be showing it?' I think it's to the credit of news organizations that they are dialing back."

NBC News said it had no indication why Cho chose it for his message. A Postal Service time stamp shows it was mailed at 9:01 a.m. Monday, during the two hours between his first shooting at a Virginia Tech dorm and his massacre at a classroom building.