I have worked in a large number of places--farm, factory, retail, professional, and educational. I have never seen anyone fired in such a manner as was displayed in the video, even for the most egregious infractions. It is always handled in a much more dignified and much less disruptive fashion.
I don't think that what happened to that girl will prepare her for a career in any way, unless she goes into mixed martial arts cage fighting.
I will admit that I wrote my first post or two in this thread without watching the video. I am a teacher; I know what a disruptive student looks like. I decided I should watch it since I was pontificating so much and I actually gasped loudly and said "oh my God". And I'm alone. It was worse than I imagined.
I struggle to think of any circumstances under which the actions of that officer would be the appropriate response. She was clearly not posing a threat to herself or to anyone nearby. Even if she had a weapon, say a firearm, the manner in which he tossed her around would seem to endanger those around her. I think the students nearby were in much more danger of being clocked by a flying desk than from the defiant texter, for lack of a better term. And as others have pointed out, the whole incident was extremely disruptive. I doubt that anyone was able to focus on their Algebra right after. Probably it will continue to be a distraction for a long time. Trust in, and respect for, the teachers and officers in the school has been further eroded. Even if it had served a positive purpose, I think that what I saw was morally reprehensible, but I believe that it didn't even further the intended purpose of calming the classroom environment or instilling respect for authority. Lose-Lose IMO