Its success also attracted a backlash from humanitarian aid officials, who said it overly simplified a complex issue, and from people in Uganda and other countries affected by Mr. Kony’s brutal rebel group, the Lord’s Resistance Army, who resented the video’s presentation of young white Americans banding together to save Africans.

But amid the criticism, many have been taking notes.

Early on, the video spread most rapidly among people under 25, a fact that struck Marc DuBois, executive director of the British office of Médecins Sans Frontières, or Doctors Without Borders, as a watershed. He said that Invisible Children demonstrated the potential of youthful idealism to raise not just awareness of a cause, but also money for it.

“We kind of aim at the upwardly mobile, the class that reads literature, that travels internationally,” he said, speaking in an unofficial capacity about his nonprofit colleagues. “Kids aren’t going to make a $10,000 donation like a major donor, but they’re going to do it in small bits. And they will contribute. And their parents will.”

The campaign took in hundreds of thousands of dollars on its first day alone.

“The lessons that nonprofit organizations can take from this are that savvy media and marketing matter,” said Dan Pallotta, the president of Advertising for Humanity, a for-profit company that works on charitable causes. He said that resistance to “anything that smacks of being commercial” had kept established organizations from spending more to promote their message.

The coordination of the video, called “Kony 2012,” with a social media campaign focused on enlisting celebrities, including Oprah Winfrey and the pop star Justin Bieber, provided another avenue to reach young people and another lesson for more established groups, experts in social media said. Invisible Children also showed a rare willingness to engage with people on social media, including when the talk turned critical.