There are an awful lot of assumptions being made here, which aren't necessarily supported by the only evidence we have - the video. We can't know if the lorry driver could have seen the cyclist, or where his attention was. We know nothing about the lorry other than it was pulling away as the cyclist passed it on its nearside - a manoeuvre known by all of us to be unwise and sometimes fatal. The only person whose actions we can judge is the cyclist: he was riding very quickly for the space available, he appears to take a relaxed attitude to risk, and he seemed not to allow for the inadequacies of those he shared that road with. Therefore, my take is that he did much to bring the accident upon himself.
The fact that lorries have large blind spots is not news. All vehicles have blind spots to a greater or lesser degree, as do human heads. While it is obviously incumbent upon us all to do our best to look around us and be aware of what surrounds us, it isn't possible to be all-seeing. Therefore it is also essential that we are predictable, courteous, and look after our own safety. This rider failed on at least two of these criteria. It isn't always someone else's fault, however much we'd like to believe so.