It's a merge in turn. Merge in turns work well if that's what people do instead of blocking each other's way. This van driver had a choice of remaining on the roundabout blocking it up or moving into the empty lane there.
A merge in turn works like a funnel to get traffic through a junction from different directions and down a road efficiently in the same way it's been proven putting a bollard in front of a doorway so people approach it from the sides and merge into one line gets people through faster than them approaching it in one line straight on.