Sure, but sometimes the officer is the first to use aggression. I completely disagree with initiating violent force. How can you know he will punch you until he swings?
A few things, if you are trained and experienced in noticing the.
1. Scanning. The suspect isn't looking at the interviewer. He is looking at the surrounding environment. He looks like he is looking for something, and is. He is looking for back up officers, witnesses, escape routes, allies.
2. Target glance. The suspect looks at specific areas on the officer. Where is their gun? Do they have a taser, pepper spray? Where is their radio and/or hand Mike. If they stay focused on a weapon you might want to be prepared for weapon retention. If they finally start looking at you face be prepared for a punch.
3. Clenching. constriction of muscles indicates physical stress and perhaps readiness for an attack. Pre-fight tensions will cause jaw muscle to bulge, fists to close and facial muscles to contract. If you pay close attention you may observe the trapezius muscles rise as the large muscles of the body constrict as if to prepare for physical contact or assault.
4. Eye blinks. Two variations. Some people will slow their blinking and get the thousand yard stars. Others will double, even triple their blinking rate (average rate is about 20 per minute.
5. Taking a fighters stance.
6. They flank the officer.
Unless the person is under the effects of an intoxicant or suffering a mental health episode it is actually not difficult to see the subconscious "tells" that an assault is imminent. Add these in with a known criminal history, especially one of violence, maybe they are on Probation/parole. This is why knowing these queues are important for an officer. An officer doesn't have to wait to be punched before they act, but they need to know the cues and how to articulate them to do so legally.
I already conceded on the video where the officer was arrested. Like I said, 10-15 minutes to gather proof when I start with a vague memory? Search "Police Shooting" on YouTube and you get much more hits against police than supporting police.
I hadn't seen the update, but the suspect is resisting while the officer has a pistol on his spine with additional officers around. Not a lot of perceived danger from my perspective. And he was arrested because it was obviously suspect of wrong doing.
YouTube is a HORRIBLE source for this. Except in extreme circumstances they are usually myopic in scope and show only the immediate incident of violence. This is a perfect example as to why you don't trust YouTube, especially with bias filled search terms.
Two other issues as examples.
Alton Sterling. Even the Washington Post experts could only say this upon closely watching the video. Note the source here isn't what I would call police friendly...
Was Alton Sterling shooting appropriate use of force? Experts analyze video for Washington Post
What does that all say? That the officers arguably made tactical mistakes, that due to lack of empty hand training were out of options when the taser failed and that because of this cascade the shooting of Sterling is actually within the use of force.
Then we have what one person started spreading on FB about the shooting of Scott on FB. A friend shared it saying "omg I hope it isn't true" because the YouTuber is editorializing. At one point he says "see they dropped a gun. Omg they dropped another gun, this is a set up!!! Now the guns are gone.". Because of my friends preconceptions exaggerated by the editorial, they saw guns. They weren't. It was the nitrile gloves the officer, who shot Scott, was struggling to put on due to the stress, so he could help render first aid.
YouTube, tbh Social Media in general, sucks.