Personally, I believe people learn A LOT about discover & the movement when they figure it out on their own. Sure it's nice to have some sort of guide or teacher, but I believe once they are told exactly what to do, how to take off, how to plant the hands, how to jump etc... it just limits their imagination and personality in Parkour. People should move how they are comfortable through their environment, not conforming to a list of vaults. Sure, handy, yeah, but again I think it just limits movement because instead of thinking, "Ok, that obstacle is there, what can I do to most efficiently get over it" rather than, "Ok, that obstacle there, I'm going to pick a vault that I've learned to get over it" See the difference?
But, this is just me... I did Parkour for 8 months before joining my local community. In that time I taught myself all the basics, and I
know I have a better understanding of them, than if I just resorted to watching tutorials and having it tell me what to do.
It's amazing how little variety/imagination is in Parkour videos these days :/ They all consist of.. pretty much the same thing to be honest. Though there are still those out there that are very creative and different.
Oh, and the amount of Parkour tutorials is.. quite frankly... retarded.

Some things that don't need tutorials... have tutorials!!
I can understand things like... conditioning tutorials and such, but something like movement doesn't
need a tutorial, but everyone is different and has different beliefs and feel the faster they learn the vaults the better I suppose :/
To each his own I guess.
To ask beginners to repeat lour mistakes and missteps would be a great disservice I think. I'd like to avoid the saying "history repeats itself." If I know that coming out a roll in this direction will hurt my hip bone, why should those that come after me have to hurt themselves to learn the same fact?
I agree, but I still believe, since Parkour is basically, about discovery, and living!
It's still great to learn things on your own, to have a better understanding of the technique, as well as to challenge your mind to break a movement down and figure out what it is you have to do to figure it out. What is the rush to learning a movement? 
Think of Bruce Lee and martial arts/physical fitness for a parallel. He experimented on new workout routines, diets, and techniques to decide what worked and what was useless or not of enough merit. He then passed down these teachings in the hopes that others would learn and build on his work.
Yes, Bruce Lee was an amazing individual, yet no one really compares *yet* to his physical ability, so it's hard to build off of such a strong individual or surpass if others don't experience what he experienced/get to the level he was at, if that makes sense haha