I'm sure officer.com weighed in on it, but for those that haven't seen their response, let me give you mine as an officer.
First off, her command voice and authority sucked. She NEVER provided him with clear, concise instructions. Through the entire thing she did nothing more than badger, insult and demean him. She entered into this entire stop emotionally charged and ready to fight this guy. Her forceful coughing on the video prior to initializing the traffic stop was enough for me to realize she was physically charged up before making the stop.
Second, her demeanor completely and utterly lacked in professionalism. From the very first use of profanity, she failed. Never mind the fact of her removing the guy from his vehicle like she did. I'm sure she suspected him of DUI as a reason for the stop, so why would you EVER ask a drunk to get out of their vehicle on an interstate road and risk him/her tumbling into traffic. Stupid, stupid, stupid incompetent mistake.
Third, she should have had him sit down on the embankment, called for backup and waited for assistance. This only further shows her state of mind as being charged up, but also points to her incompetence.
Fourth, she should have sprayed him with OC when he resisted the cuffs. One verbal warning, then whip out the canister and spray. She also potentially blew the entire DUI conviction when he stated he had a physical impairment (besides the alcohol) but she still made him participate in the field sobriety test (FST). When she used the HGN test (the pen and eyes test) on him, she should have been able to guage his level of intoxication from that alone. Granted, in most states HGN is not admissible in a DUI case, but it would have been enough for her to apprehend once he said he couldn't participate in the FST.
I don't see any point in this entire thing where she could have felt threatened enough to fire her weapon at this guy, much less threaten him with it. It's a travesty that she's not fired or charged with a crime for that matter. If any of my officers were ever this incompetent, I'd have them removed from service immediately and I would write a scathing report on their inability to conduct themselves in their duties. That is all.