Youtube doesn't work in any browser

Hello,

I can't view any youtube video. The image appears for 1/2 second then i have a black square with the sound. I tried with viewtube, but this is even worse, the video plays normally during 1/2 seconds then stops and replace the image with a black square with an error message above: "ViewTube. Couldn't get the videos content. Please report it here".

Is there a solution ? Thanks.