strange beeping car video

Or stop right in the middle

Or stop right in the middle of the lane. Get off, and very ostentatiously check that everything is OK on your bike. Maybe even then go up to them and ask what they were warning you about…

Edit: maybe that would be unnecessarily confrontational? 😉

Only the official reason, to
Only the official reason, to warn another road user of their presence.

But…. 3 men make a tiger as the saying goes. One beep, you think crazy old man, 2 beeps you start to wonder, 3 beeps and maybe you should check for tigers, or your luggage falling off or your bike being on fire or something else you might not have noticed.

If I were the biker and from what I could see in the video, I think I might have used the opportunity of the lorry blocking the entire road to get to the head of the queue and then find myself some clear road space once it had cleared. But if unsure, e.g possibility of lorry having to take a second attempt, always better to stop as the biker did.

Maybe to warn you about the

Maybe to warn you about the lorry?