Facebook CEO Mark Zuckerberg delivers the keynote address at Facebook's F8 Developer Conference on April 18, 2017 at McEnery Convention Center in San Jose, California.

Carolyn Everson, Facebook's vice president of global marketing solutions, regularly sends out video messages to communicate with the company's internal ad-sales teams.

But in mid-February, Everson did something unusual: She recorded a video for clients explaining what Facebook was doing to prevent ads from ending up next to undesirable content.

She sent the video to a group of advertising agencies and consumer brands that represent some of the company's biggest ad buyers.

Among the topics discussed was how Facebook was working to combat hate speech, terrorism and what the company calls "false news."

The decision by Everson to share the video with Facebook's Client Council shows how concerned the company and its customers are about the problem of misinformation. Rival Google is, too.

"They're both taking this very seriously," said John Montgomery, executive vice president for brand safety at GroupM, a unit of the giant ad agency WPP.

A Facebook spokesperson explained, "We regularly share updates with our advertising partners around the world. This is one example of those communications."

False news is an issue that rears up each time misinformation and other inaccurate stories spread on Facebook and YouTube following mass shootings like the one in Florida in February and Las Vegas in October.

"Every time something like this happens, it undermines confidence in social as a platform" for brand advertising, said Montgomery, an industry veteran who speaks with Facebook, Google and large brands on a weekly basis.

Some of the posts that followed the Florida high school shootings are a reminder that "no un-curated social advertising is 100 percent safe," he said.

The latest round of false social media-conspiracy theories following a mass shooting came two weeks after CEO Mark Zuckerberg said on an earnings conference call that "preventing false news, hate speech and other abuse is another important area of focus for us."

In a speech Wednesday, Facebook COO Sheryl Sandberg gave a clear account of the nature of the problem.

"People are writing outlandish headlines so they can get clicks and can get ad money, so probably the most important thing we can do is go after the economic incentives," Sandberg told the audience of investors at the Morgan Stanley Technology, Media and Telecom conference.

Facebook wants to "make sure the people who are purveying false news are not making money on it," Sandberg said.

Much of the source of false news on the platform is "fake accounts," she said.