I know I'm new and all, but I don't see what is so bad about "parkouring." One example I could come up with that uses a word in this sense is that of "kiting" for people who are flying a kite. "Kite" is a noun. This seems like a matter of definition. Not in the sense that parkour is an artform and a borrowed noun...but I mean defined by people. As far as words go, if everyone agrees on what to call something, then that's what it is. If everyone calls those purple and green fruits that wine is made out of "grapes," then they are "grapes." If everyone agrees to use a particular verb form of parkour, then that's how it will be known. It doesn't seem right to me that language is constant and doesn't change, evolve, or add new things over time. I can't argue with the linguistics major though.
Just my thoughts.
Thanks.
Parkour is a noun, and has no verb form, that much you understand. The part of speech you're speaking about is called a gerund. It is a verb masquerading as a noun. But a noun, in any way, shape, or form, may be used as a verb. You see, the word kite has a verb form these are kiting, kited, and kites. By saying you're partaking in kiting is correctly using the word. But you did not take a noun and turn it into a verb, it was already a verb in the first place.
If parkour was a verb like you suggest it should be, then parkouring would be the gerund form:
I like to parkour.
Parkouring is my favorite thing to do.
However you cannot change a noun into a verb. It just isn't possible.