MOUNT LAUREL, N.J. — An electronics store clerk credited with providing the tip that broke up an alleged plot to kill soldiers at Fort Dix went public yesterday, saying he spent a day pondering his suspicions before going to authorities.

Brian Morgenstern said he was alarmed when he watched the video two men brought him to have transferred to a DVD, but also worried about invading the customers’ privacy.

“I was considering whether or not this was really a threat, or something serious,” he said. “I came to the conclusion that that’s not my job or decision to make.”

After three weeks of being hailed as an anonymous hero by law enforcement and on newspaper editorial pages, he came forward with a series of media interviews yesterday, the first on CNN’s “American Morning.”

Mr. Morgenstern, a clerk at a Circuit City store, described how two men brought him a videotape to transfer to DVD in January 2006.

He said he went home that night and told his family what he had seen: Ten men at a firing range with handguns, rifles and what he thought were fully automatic rifles. He said authorities have asked him not to divulge some details of the video. But authorities later said the men were chanting “God is Great” in Arabic.

When he heard the news of the arrests, Mr. Morgenstern did not even realize his role in the investigation.

But after a news conference in which he was praised — but not by name — he knew.

A special agent in charge of the FBI’s Philadelphia office, J.P. Weis, called Mr. Morgenstern “that unsung hero … who saw a video and said, ‘You know, somebody needs to know about this.’ And that’s why we’re here today, thanks to the courage and heroism of that individual.”