I suppose, looking at it in another way, passer-by sees a crime being committed, someone smacking someone round the head and running off with their mobile phone. Passer-by records it on his mobile phone, posts it on social media and sends a copy to the police. Now instead of nicking a phone which is breaking the law, insert using a hand-held device whilst driving, which is also breaking the law.
Personally I'm fed up with the numpties on social media who post "shock" dashcam video clips, most of whom have little or no knowledge of the Highway Code or other rules of the road. It seems you've been a victim of one of them. But be aware of the rules regarding the use of phones whilst driving, there's a lot of police chase videos spouting off about that matter. If you're lucky the video may not reach the police, if you're not, it's £100 and 6 points IIRC and two minutes of internet fame for the dashcam warrior.