Heres a graphic video of the possible injuries a DGI Phantom with carbon blades can cause. This guy is in a park trying it out just like any park flier pilot would do. He even has prop guards on it from what I can see. For the most part things are going well until he tries something and it goes wrong.
The point is these small vehicles have a lot of power for their size and in a novice hands around the public open areas like parks, etc, its only a matter of time before more serious injuries happen.
We have seen at our club while performing for special needs kids one of them chasing after a taxiing plane. In a park without people spotting for the pilot its very easy to imagine child running to grab a copter especially a DGI because it looks like a toy.
Anyways, more support for getting people to realize the responsibility of owning and operating these AC and why they need to be regulated in some form.
http://www.liveleak.com/view?i=8d9_1407980380