I just found out that the concert will be broadcast live on the internet !
http://www.code-making-machine.com/mainSquare/
The message says : "For the first time this year, the Main Square Festival offers everyone the opportunity to attend their favourite artists' concerts !
From July 3 to 5, every day, several concerts will be broadcast live, for free and with no advertising, on the festival website http://www.mainsquarefestival.fr.
All Muse fans who could not get tickets for Saturday, July 4 will have the opportunity to watch live the full gig. It's the same for Rival Sons, Madeon,George Ezra, Sheppard, Oscar And The Wolf and Rone (among others) !
Full details will be available from Thursday, July the 2nd on http://www.mainsquarefestival.fr."
Sorry for the possible mistakes, my English is not perfect at all !