There's also competitive parkour with international tournaments called World Chase Tag. Think game of tag but with acrobatics: https://youtu.be/Ea_Mkmj92PY
I'll be honest and say I didn't follow the back half too closely. Is it the author's intent to say that parkour is purely viral in it's transmission from person to person? I would think any child left on a jungle gym (outdoor playset if the term's regional) for more than 5 minutes would be attempting the same thing without prompting, at least to their own abilities. The human mind likes to problem solve and find shortcuts, parkour is an extension of that.
I think "Paris sportif" translates directly to sports betting. So while in this context it's probably supposed to mean something like active/sporty Paris, I don't think the title works.
I thought is was a deliberate pun. Maybe something along the lines of "The city of Paris is trying to develop parkour and capitalize on it", with the bet being used in a business sense. Turned out there is nothing looking like a bet in the article and it is just a poor choice of words instead.
"Paris sportif" really means "sporty Paris". "Sports betting" would translate to "Paris sportifs" (plural) or "Pari sportif" (singular). It is quite subtle, that's why I expected it to be a clever pun.
It means both, depending on you deciding it's paris (bet) or Paris (the city). It did lead me to expect something else from the article though - I was expecting more gambling, so I guess you're right about it being slightly misleading.