I was very shy as a youngster. I would NEVER do what this young man did. But this is something that should certainly be encouraged. Schools (& parents) should be encouraging it.
I as well. I found that forced public speaking, starting in school, doing presentations, helped a lot. I even took a public speaking class in college. The teacher gave us simple rules about preparation, and said basically - its ALL just regular practice and becoming comfortable with speaking - overcoming one's fear through using a simple format, preparation and constant practice / repetition.
I've since spoken at industry conferences and such, in front of hundreds of people. I don't know if I could do what someone like Charlie Kirk did, ie) ad hoc, extemporaneous debate in front of thousands, but I suppose with some practice, even that is possible.