They charged them with receiving stolen goods. How this relates to French Law I'm not aware tho.
Me downloading a movie is normally civil. This new case turns it criminal.
Copyright and patent violations fell under criminal law some years ago. There was a long battle in the EU to stop this happening. The movie industry won. In France the law was passed under Sarkozy iirc.
When you download a movie, this is now a criminal offense. However the sanctions are mild (warnings) for first time offenders, and only turn to jail time for those making a lot of money from it (I think, IANAL.)
In all cases however the rights holders don't sue, it's the state that sues. Big win for the content cartels as they get these cases prosecuted for free now.
Yes, potentially some people will go out to see the movie if they cannot pirate it. But not all. And it's hard to prove either way.
That's not the same as "stealing a car".