Decius, if you consider these people to be 'posers' but then simutaneously stating that it may be beautiful and spectacular, negates the fact that they are athletes in martial arts, gymnastics and climbing after many years of training. The 2nd and 3rd video actually feature the founder of Parkour- David Belle.
those that do parkour for themselves, for their souls, for the art or physical challenge, have no need for others' approval and therefore, have no need to be seen as "cool".
So whats the point of watching an actor in a movie or a tv show, going to a sporting event, going to an art museum, reading a book, listening to music or perhaps presenting your occupation through different mediums. Even more so- whats the point of being the protagonist itself. Why not publicise one's skills. You need to understand that the essence of parkour is absolutely not exculsively about posing. Sure it may seem to you, but its not if you look into it. Parkour is about the rythmic elegance of mind and body. Understanding the philosophy of Parkour, is more than simple movement or performance of the movement. Parkour requires fludity, balance and smoothness. Its about focusing your attention to your mind, more than to the outside physical world. Its about following your own path, your intuition, to make progress step by step. Not to forget that its a lot of fun as well.
The below video, will help.