"YouTube is not all cat videos and aspiring musicians. There are a ton of other things on there that have a nefarious nature and often are pushing illegal or illicit activities," DCA Deputy Executive Director Adam Benson said.
Digital Citizens Alliance, an industry and consumer group, worked with the Global Intellectual Property Enforcement Center (GIPEC)to conduct searches and review videos in New Hampshire, South Carolina and Virginia in the days before the primaries in those states.
The advocacy group is funded by the "creative, pharmaceutical and tech industry." Digital Citizens Alliance doesn't disclose specific donors because of concerns about the sensitive nature of its work on the so-called dark Web. This study was paid for by money from its general fund.
Researchers attempted to simulate the experience of someone who was politically active, as well as someone not paying attention to the campaign, using both used and "clean" computers with cleared histories, the report said.
Benson said that money from such ads could potentially be funding extremist groups and other illegal activity.
Not all of the ads were produced by the campaigns directly. Some pro-candidate advertisers were unknown and some were paid by super PACs.
"We are looking into the report's findings and will take any steps possible and necessary to remedy the situation," said Connie Wehrkamp, communication director for New Day for America.
The five campaigns have not responded to ABC News’ request for comment.
DCA’s Benson said, "We don’t see an easy fix for the campaigns. For a lot of the kinds of ads that we saw, they want their messages spread far and wide. If you do that on YouTube, you’re going to run into these kinds of videos.”
American University communications professor Scott Talan said these pairings shouldn't come as a surprise.
"The candidates don’t control where their ads go," he said. "But, of course, this is highly embarrassing for all the candidates on both sides."
He added: "You have to wonder are candidates getting what they're paying for?"
"Ads have accompanied jihadi videos on YouTube for a long time, and in election season, it’s not surprising that political ads would be among them,” said Rita Katz, executive director of SITE Intelligence Group, a private organization that tracks and analyzes global terrorism.
Katz said her primary question is why these videos are allowed to remain on YouTube.
"Social media companies have been aware for a long time that jihadists disseminate propaganda on their platforms. However, very little has been done to change this reality," she said.
YouTube points out that its policies prohibit content related to dangerous or illegal activities and terrorism.
"YouTube's teams review videos that are flagged around the clock, and work quickly to remove material that violates our policies,” a YouTube representative said. “We also have stringent advertising guidelines, and work to prevent ads appearing against any video, channel or page once we determine that the content is not appropriate for our advertising partners.”
YouTube’s website states that it has a variety of targeting options that help reach the right customers. Advertisers can target by age, gender, location and interests, according to YouTube.
But it is unclear what specific controls either YouTube or the campaigns would have to prevent specific ad-content pairings.