In most cases if you rear end someone you are at fault because rule of the road says you should have been within breaking distance of anyone in front. Thanks to your dashcam you had solid proof the person in front was at fault and no collision because you took good evasive action. I read stories people would go out late at night in city center drive good speed in front of someone then right before a traffic light which was green slam on the breaks in the hope of a rear end collision to collect from others insurance. They say late at night less witnesses and good chance other person is DUI or not alert. They tell the police they stopped because light had turned red. It becomes his word against the word of whoever rear ended them. I can see it happening if they want to take risk of injury. Good idea with the dashcam. We all have close calls at sometime. You were lucky, stay safe.
