Some of us do not have any of the above and get to experience the exhilaration of galloping full tilt, bareback, helmetless in shorts and bare feet, galloping bareback with a halter and lead rope, swimming, jumping things you should not be jumping, riding in bad weather or on not so great surfaces, maybe thinking it's fun to teach a horse to rear because we have no problem sitting it (again, lack of adult supervision is key here), seeing how high we could jump (bareback) or whatever.
I was one of the second type of kids and it looks like the kid in the video is also on that group as well. I can not imagine being surrounded by adults who are not paying attention and leaving me to my own devices and then having a different bunch of adults bash me for it. Geesh. If anything, it is the adults in this girls life that should be taken to task for the risks this girl is taking.
I did not watch the other videos but really see nothing wrong with the original link. Some of it is not pretty but that is a compilation that the kid put together for effect so I'm doubting she is riding her horse like that all the time and it is obvious she loves him. She is a teen besotted with her horse. Hopefully she and her horse will survive and she will have to leard from her mistakes because I guess no-one is teaching her but if she sticks with it she will know some things the kids in the first group won't and she will be a decent rider as well. She appears to have a decent seat bareback over some of those jumps, especially towards the end of the video.