Videos of police officers battering or even killing unarmed black civilians have given the wider society a view of the world in which African-Americans have lived for a long time. President Obama has referred to this history on several occasions, noting that video from cellphones and body cameras have shown the country that black Americans were not imagining the problem of police brutality or “making this up.”

But the link between these videos and the racial history of United States seems to have eluded James Comey, the director of the Federal Bureau of Investigation, who appears to be fixated on the discredited idea that videos represent a problem in themselves — and that the police are less willing to do their jobs because of them.

Mr. Comey came under intense criticism when he raised this idea in a speech last fall. He repeated the idea at a news briefing in Washington last week, when he said that speaking to police officials around the country had led him to believe that a “viral video effect” had made officers wary of confronting suspects and “could well be at the heart” of an increase in crime in some places.

Law enforcement organizations are outraged. The National Fraternal Order of Police accused Mr. Comey of saying the police officers were afraid of doing their jobs. Law Enforcement Leaders to Reduce Crime and Incarceration, a group of more than 165 police chiefs and prosecutors, denounced the “viral video” comment as "unfounded, and frankly, damaging to the efforts of law enforcement.”