They began as workaday interactions between the police and the public, often involving minor traffic stops in places like Cincinnati; North Charleston, S.C.; and Waller County, Tex. But they swiftly escalated into violent encounters. And all were captured on video.

Those videos, all involving white officers and black civilians, have become ingrained in the nation’s consciousness — to many people, as evidence of bad police conduct. And while they represent just a tiny fraction of police behavior — those that show respectful, peaceful interactions do not make the 24-hour cable news — they have begun to alter public views of police use of force and race relations, experts and police officials say.

Videos have provided “corroboration of what African-Americans have been saying for years,” said Paul Butler, a professor at Georgetown University Law School and a former prosecutor, who called them “the C-Span of the streets.” On Thursday, the family of Samuel DuBose, an unarmed black man who was shot to death by a University of Cincinnati police officer on July 19, said the officer would never have been prosecuted if his actions had not been captured by the body camera the officer was wearing.