The assault raised concerns about the treatment of American Indians by police in towns that border the Navajo Nation Indian Reservation, tribal officials said.
Frazier, 57, was sentenced to three to five years probation in U.S. District Court in Albuquerque.
Though he will avoid prison time, Frazier will not be able to work in law enforcement or own a gun as a condition of his plea agreement, said Arlon Stoker, the attorney representing Donovan Tanner, the victim.
The former deputy allegedly struck Tanner, 24, multiple times with a flashlight in Farmington on March 17, 2011, according to a news release from the sheriff's office. The beating, which happened the night of St. Patrick's Day near Three Rivers Brewery in downtown Farmington, was recorded on the camera inside Frazier's patrol car.
The video, which was released by the sheriff's office about two weeks after the assault, shows Frazier ordering Tanner and his brother to stand near Frazier's patrol car and answer questions about an argument at the brewery earlier that night.
Frazier can be seen pinning Tanner to the hood of his car. He first uses the flashlight to choke Tanner and then starts hitting him in the head, neck and body. Tanner falls to the ground, and Frazier continues delivering blows while a Farmington police officer and sheriff's deputy watch.
As the video circulated on YouTube, a video-sharing website, it raised concerns on the Navajo Nation Indian Reservation about police department's relying on force in American Indian border towns, said Leonard Gorman, the executive director of the Navajo Nation Human Rights Commission.
"As my office sees it, Navajo Nation residents are very concerned about law enforcement in all border towns," Gorman said Wednesday. "There is a very strong need for recognizing that these incidents do exist and that there is a need to make deliberate and strategic efforts to address these kinds of incidents."
Tanner was arrested after the incident and charged with disarming a police officer, which is a third-degree felony. The district attorneys office dismissed the charge.
Tanner "is pleased with a resolution," Stoker said. "He just didn't want this to happen to someone else."
Tanner filed a lawsuit against San Juan County. The case was settled for $250,000, Stoker said.
Frazier was placed on paid administrative leave on March 30, 2011.
He was fired from the office on April 22, 2011. He had been a deputy since June 2006.
Frazier was indicted June 27, 2012 on a charge of unlawfully assaulting a man with a dangerous weapon, according to a news release from the U.S. Department of Justice.
He was facing a maximum sentence of 10 years in prison. His trial was scheduled to begin Oct. 29.
"The public places great trust in law enforcement officers to use their authority in the right way and only the right way," U.S. Attorney Kenneth Gonzales said Wednesday in a prepared statement. "When they intentionally abuse that authority, they will be held accountable. Today, by pleading guilty to a federal felony offense, Dale Frazier was held accountable for seriously violating a young man's rights."
Stoker said Tanner hopes the incident will affect future law enforcement in the county.
"Maybe they'll think before they take out their flashlights and start beating (suspects) with them," Stoker said.