Some observations:
1. A lot of missing context - what happened PRIOR to the screaming foul mouthed woman ?
2. Could only hear her - WHAT was the male passenger saying ?
3. Why did HE get out of the passenger seat and even get close to the woman ?
4. Road rage incidents are almost always instigated by the car that is in back. Appears to me the 'two man car' was the one in the rear, and the actions of the passenger were EXTREMELY aggressive - getting out to 'confront' the woman, when it wasn't him that she was screaming at - it was the driver who was the target of her fury.
5. What was the guy saying while walking away to the woman right before the 'head slap' from behind (misdemeanor assault) ? Fighting words, threats of getting a gun?
6. WAS HER FURY JUSTIFIED ? DID THE DRIVER OF THE TWO MAN CAR PUT HER IN MORTAL DANGER ? Quite possibly.
7. Notice how quickly the two men got out of there after the assault. They obviously didn't want to wait around for the police to get there. Says a LOT.
The guy could have walked away after returning the head slap with a punch. HE DID NOT.
Instead he responded with a damn near LETHAL ATTACK.
There was NO LEGAL JUSTICATION for what he did. He should be arrested for FELONY CRIMINAL ASSAULT - and even a possible charge of attempted murder.
Like I said, a heckuva lot of 'missing info' - I think that gal was probably justified in 'losing it' and is damn lucky to still be alive.
The two in the car - show a lot of the markers for 'road ragers' who are extremely dangerous.
And yes - got just a tad bit of experience with road ragers - they are extremely dangerous, should never be approached, do not attempt to block them with your car/truck, and if you can get away from them - DO IT AS FAST AS YOU CAN SAFELY DO SO.

Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good ...