What an interesting thread, I will add the voice of reason and experience now.
There is clearly much, much more to this than we are being shown and I would hazard a guess that there is a considerable amount of interaction between these two in the run up to the clip we see.
The van driver is a knuckle dragging chimp and should not be on the road for a very long time (I consider a 12-18 month ban to be appropriate for a first offence of this nature).
The cyclist needs to wind his neck in a bit because his style of self-righteous cycling is massively increasing his risk exposure when on the road.
I am both an experienced urban cyclist (I've done it all my life) and an experienced driver. I have done the 40kpa driving job in large vans. I ride on the roads with my kids. I have an inkling of what it means to share the road with ALL users.
The person riding the cyclecam that caught all this action was using the road a bit more considerately and clearly felt that they had been passed by the van in the film without undue danger or threat, or I am sure we would also be seeing that evidence of a close pass.
It is not ideal but there really was no need for the cyclist to block the road in this manner (looks as though there was a hint of weaving going on, but without the previous footage can't be sure on this) and given the limited view of the road that we are given I am sure I wouldn't be riding so obstructively. Trust me, I am no timid gutter bunny and anyone who has ridden with me will know I am certainly not afraid of being an assertive cyclist. There was no need for that incident to become the confrontation that it did and the cyclists experience of using the road could be considerably less dangerous and a lot more enjoyable if he was not so adamant in enforcing his 'rights'!