saw this a while ago... hilarious... and particularly nice to see again having just been on the m25.. Its 4 lanes now and people STILL insist on sitting in the outside 2 lanes even if there is nothing inside them. I'm afraid I dont care anymore and I just undertake.
I've had so many who do the brakelight thing. Luckily I'm a safe distance behind when I give them a polite flash to move over and let me pass. I don't undertake anymore though. I went to do that a few years ago in my V6 4Motion, and they paniced, and went to move over just as I was undertaking. Luckily, my brakes were strong! I was at fault for undertaking, but I wouldn't have tried it in the first place if they weren't doing something so selfish and stupid.
I think they think they're 'policing the highway' making sure no-one is breaking the law! What they are doing is very dangerous, as they create anger and frustration on the roads, which causes so many accidents.