Watched it again twice and I haven't changed my mind. Clearly the van driver intends to come out, the cyclist leaves him only enough space to join the traffic at the cyclist's pace, although the van is at a standstill so realistically - and safely - could only have pulled out at the speed it did. You can clearly see that the van veers towards the kerb after the cyclist has yelled out in road rage (yes, it is) and as the cyclist attempts to slot into the margin, IMO unreasonably, and slaps the backside of the van.
In my view the cyclist didn't brake enough or give enough clearance to let the van out - it's clear the rider intended the van to pull out in front as he had left some gap for it to do so - but not enough. I think the cyclist misjudged the distance and speeds and then had a hissy fit (by his own admission on the last note).
Cyc