I also believe that the Veyron decreases downforce, even if this article doesn't mention it.

About that, in my mind, it's not that downforce decreases after 190 mph and reaches a dangerous level, i better think that downforce is increased to it's maximum level before 190mph in order to give the better grip possible.

It's not "Normal mode to low mode", but better "high grip mode to normal mode".

Anyway, the guy who crashed was in the highest mode and that didn't help him and after all, if somedy wants to drive over 190mph on a non flat or non perfect road, he must not think that 80kg of more downforce could help him.