Maybe I've just missed it but the only "attack" I saw was with the other video with the hybrid, and again, you have no idea what started it.
I was on a group ride years ago down south, a driver fed up of being (cleanly) overtaken decided to swerve in front of one of our riders. (a middle aged female teaching assistant, incidentally), and almost took her off. When he stopped in traffic, he found himself surrounded by bikes, and was duly told off. (by a labour ministerial candidate and a hairdresser, IIRC) No damage, no violence, we're all very middle-class and british.
But, if you'd seen a video starting at that point, you could easily think "All those crazy bikers hassling that guy!". Not the same situation at all, but, I can see parallels just with how things look on video.
Unless there's other vids that I've not seen, we still have no idea at all what started it. I'm still going to assume it was something the riders did, because they're cocks, but something happened to make this kick off with that one car, not the hundreds of others.