A newly-unearthed video from 2013 suggests a top aide to Hillary Clinton acknowledged the fact that sensitive information ended up on the Blackberry phones of the State Department's highest officials.

Wendy Sherman, who served as undersecretary of state under Clinton, touted as an example an instance in which Clinton met with a European Union leader while conducting sensitive negotiations on her cellphone, according to the video clip first obtained by Fox News.

"Now we have Blackberries, and it has changed the way diplomacy is done," Sherman said during a private appearance before the American Foreign Service Association. "Things appear on your Blackberries that would never be on an unclassified system, but you're out traveling. You're trying to negotiate something."

The September 2011 meeting Sherman later cited as evidence yielded emails between Clinton and her top aides that have since been marked classified.

In one of the emails from the event Sherman mentioned, Clinton consulted with another top aide, Jake Sullivan, about a meeting between Lady Catherine Ashton and "Bibi," a nickname frequently used for Israeli Prime Minister Benjamin Netanyahu.

Most of the exchange has been marked "confidential," the lowest level of classification.

Clinton has frequently defended herself against allegations of mishandling sensitive information by assuring voters that nothing she sent or received was marked classified.

However, experts have argued that officials at Clinton's level can be held responsible for the treatment of classified material regardless of whether it was marked as such.

Critics quickly seized on the new video as further evidence that Clinton presided over the rampant mistreatment of classified data.

Matthew Whitaker, executive director of the Foundation for Accountability and Civic Trust, said Tuesday the Obama administration's pursuit of the Clinton email case "has a clear conflict of interest" at stake. Clinton's private email use is presently under investigation by the FBI.

"The need to appoint special counsel with broad jurisdiction to investigate the Hillary Clinton email scandal has never been more urgent, as we learn of yet another disturbing instance of Clinton putting our national security at risk by using unsecured systems to recklessly transmit classified information," Whitaker said.

Jeff Bechdel, spokesman for the Republican political action committee America Rising, said the new clip "spells big trouble" for Clinton one week ahead of the Iowa caucus.

"Despite her numerous protests, evidence continues to grow showing Secretary Clinton knowingly sent and received classified material using her private email," Bechdel said Monday. "This new video again puts Clinton on defense, forcing the former secretary of state to explain why she put U.S. intelligence at risk by exclusively used a private email account for government business."