The No. 1 trending video on YouTube Wednesday featured a caption that included a conspiracy theory about a survivor of the Florida high school shooting.

The video — titled “Confrontation Between Lifeguard, Bodysurfer Caught on Camera in Redondo Beach Goes Viral” — was an old clip from a CBS2 broadcast, Motherboard first reported.

It showed David Hogg, one of the survivors of the Florida shooting who has become an advocate in recent days for gun control. In the video, Hogg's friend has a confrontation with a lifeguard and Hogg appears to film the interaction.

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The caption of the video — which says it was published on Feb. 20 — read: "DAVID HOGG THE ACTOR...."

YouTube later took down the video, CNN reported. The site said in a statement that the video was in violation of its policy on "harassment and bullying."

"This video should never have appeared in Trending," YouTube said in a statement. "Because the video contained footage from an authoritative news source, our system misclassified it.

"As soon as we became aware of the video, we removed it from Trending and from YouTube for violating our policies. We are working to improve our systems moving forward."

Survivors of the Florida school shooting in recent days have become the subjects of conspiracy theories.

On Tuesday, a Florida state lawmaker's aide was fired hours after claiming two survivors of the Florida high school shooting who had appeared on television were actors.

Benjamin Kelly, an aide to state Rep. Shawn Harrison (R), emailed a Tampa Bay Times reporter after Hogg and Emma González called for legislation to stop gun violence in an appearance on CNN.

According to Tampa Bay Times reporter Alex Leary, the staffer said, "Both kids in the picture are not students here but actors that travel to various crisis when they happen."

Hogg on Tuesday pushed back against conspiracy theories aimed at him, saying he is not a "crisis actor," but someone who had to live through the tragedy.

Hogg also criticized Donald Trump Jr. Don John Trump'Tiger King' star Joe Exotic requests pardon from Trump: 'Be my hero please' Zaid Jilani discusses Trump's move to cancel racial sensitivity training at federal agencies Trump International Hotel in Vancouver closes permanently MORE for giving credence to social media posts that suggest he and other students are being coached or are plants for liberal groups.

"It's immature, rude, and inhuman for these people to destroy the people trying to prevent the death of the future of America because they won't," Hogg told BuzzFeed News.

This story was updated at 12:58 p.m.