Public Servants, like the Police Officers, are bound by their duty to still ensure subjects are placed under arrest within the Force Doctrine
In fact, all officers are required to go through unarmed drills for situations such as the one in the video. What was seen on the video was 'part of the force doctrine that the officers had already executed' in unarmed drills.
At the end of the day, we must remember that our police officers are not out to brutally injure anyone. There are here to protect life and property, to defend, and detect crime.