On one hand, I can't think of many above-board reasons that a restaurant employee would tackle you for having a tiny camera, or rip up medical documentation. On the other hand, the jump straight to a mafia seems a leap too far. Yet if we are going to speculate, I don't see a criminal explanation as significantly more plausible than others.
To demonstrate one of my own: Perhaps they'd recently had a bad rating/inspection from the French/Parisian health department (replace with proper name), and were really worried about some undercover story by local news stations. A bit extreme to use physical intimidation, but perhaps the manager is on the verge of losing the place?
What about French laws related to health (are they like NYC and trying to enforce health policy through food ingredient restrictions?) Could that be something they would not want getting out by accident?
What about French labor or immigration law? Could there be some violation that they didn't want documentary evidence of?
McDonald's as a corporation protects the intellectual property of their operations with great effort (but usually in the court of law--as when a manager might try to start their own burger place using the official playbook). Not sure what competitive advantage he could get from a few minutes in the store, though.
But all of these really hinge on the employees thinking that the wearer a) wasn't a government official or inspector (confrontation would just bring more heat and/or b) that the wearer was of lower or weaker status. Mall cop enforcing a poorly understood "no pictures of the mall" policy over-zealously seems like the most likely case--maybe rooted in anti-terrorism paranoia.
(Or else maybe the guy made the mistake of ordering a Royale with Cheese and these employees were not Tarantino fans...)
On top of that, "concern about the health department" has a much higher prior probability than "mafia collusion with major fast food chain".
Granted, not usually by someone with the camera literally attached to his head.
And of the other two, Perp-1 seemed to have been the manager, while Perp-2 was a customer (judging by the shades in his hair, and the "meal" in front of him).
I'm guessing the customer felt paranoid from the camera and complained to the manager.
I'm not even sure what you mean by "random" in this case; we're talking about one event. I didn't say anything about the distribution of violent assholes in McDonalds or France in general. It certainly wasn't "random" when the first violent guy brings over other employees who happened to also be violent. I don't know about France, but in the US, there are strict laws on what a commercial establishment can do to get someone off the premises. Now, mafia-run operations aside, most places would just ask you to leave and threaten to call the cops if you remain.
I seriously cannot tell, and you didn't wink at the end?
Since McDonald's are easily franchise-able, I suppose they could legitimately be used as a Mafia Front... But really, Poe's Law? wink ;)