This story doesn't make sense: it's not clear who hit who, whether you were scamming them by not giving insurance, or how a dash cam would help when no real damage was done.
The older couple hit him, with their motionless, parking-braked vehicle. Possibly by using dark matter/energy to cause space-time expansion that pushed his car into theirs.
Snow storm detail indicates the road may have been slippery. They might have locked their wheels on an icy hill and skated into the other car. It happens a lot where I live.