Not that dangerous? He's all over his side of the carriageway, pays no regard to door zones, overtakes at ridiculous pinch points, takes no account of hazards such as side turnings, and rides in an urban environment that minimises his chance of being able to safely take action if things go a bit bobby. It's hard to say from the footage but I suspect his head never moved more than 5 degrees either side of pointed straight ahead.
I'm sure it's great fun, but he needs to think about the difference between fast riding and fast risk taking if he wants a long and healthy life.