Interesting discussion, clearly the size and speed crosses the 'scary' threshold. I wouldn't worry too much about that however as the risk is small, people invest a lot of time and effort into building models and that investment means that it is very very painful for them if they crash them. In many ways the modeller has more invested in the outcome than onlookers or the folks in the area.

That said, its an amazing to me this guy can keep his head 'in the plane' which is to say at that speed can fly the plane to its orientation rather than his own. When I've flown model planes there are always times where I'm turning the wrong way because I've mixed up the front back / left right controls given a particular plane attitude and direction. (and yes crashed a couple which made me feel horrible and so I stick to vehicles :-)

Next up I hope someone can build a FPOV version so they can fly it from the "cockpit". That would also make for a great video.