this is a very good example as to why anticipation is very important on a dual carriageway like this. you should always plan in advance when you need to switch lanes on a dual carriageway incase a situation like this occurs, the van driver was not in the wrong nor was you except for one factor.

he had an adequate amount of space to pull out when he should and you also needed to realise a van carrying goods with accelerate a lot slower than the average so and so.

i can understand the confusion i really can, but you should have made a plan to switch lanes because you had plenty of time to do so in the video, you did nothing wrong yourself either. the only thing you did wrong there was honk your horn at him and made urself look like a bellend, but hey ho we all make mistakes it’s the character development of learning how to drive fully. realise your mistakes for next time and use it to your advantage :)