"I'm going to let the release of that speak for itself, but yes, I definitely have concerns after watching that video," Barrett told reporters Monday.
Barrett said Police Chief Alfonso Morales had a similar reaction to the video, which could be made public as soon as Wednesday.
Police officers used a stun gun on Brown and arrested the then-22-year-old guard during questioning over a parking violation in a Walgreens parking lot at about 2 a.m. on Jan. 26. Sources who have seen the?body-camera footage told the Milwaukee Journal Sentinel that Brown was not at all combative before officers used the stun gun.
"This could be bad," a source told the Journal Sentinel of the video. "The player doesn't appear to be provocative at all."
Barrett said multiple times that he was concerned about the officers' actions in the video. Police have shown the footage to some local officials, including a closed session of a Common Council committee.
The officers involved in the incident are the subject of an internal investigation. Brown was not charged after his arrest for resisting or obstructing an officer.
"There's going to be a video that's going to come out soon, in the next couple of weeks, involving the department," Assistant Police Chief Michael Brunson Sr. told a church congregation on Sunday, according to WITI-TV. "And I'm going to be honest with you, we're going to need your support during the challenges."
The Bucks signed the 6-foot-6 guard from SMU last summer in a deal with the Philadelphia 76ers, who selected him in the second round of the 2017 draft. He averaged 4.0 points and 2.6 rebounds this season.
The Associated Press contributed to this report.