I've ridden this road quite a few times (just past where the video is the road gets twisty and very nice ride up and down the other side of the mountain)...
not sure they go into it in the video but the cars on the other side of the road are a funeral procession. typically in the south of the US, when there is a funeral procession (front car- hearse) had already turned off the road to the right (riders left) so you miss that part. the cars are going slow and the cars in front of the rider were pulling over to show respect to the funeral.
Might have been a better idea to pull out of the road way if you are going to stop, but either way the person driving the pickup that rear ended the car and missed the bikes was just not paying attention.
I got rear ended four weeks ago in the wifes E46. I had been stopped on a straight 2 lane road with clear line of sight for 1/2 mile. brake lights on, turn signal on, another car behind me, third driver just didn't see us sitting there and hit both of us...
pay attention out there and stay frosty!