Are you talking about the video or the audio? Check that all software and drivers are up to date.

I talk about the audio ! All drivers are up to date, I already checked, I suspect that is the extensions or the latest updates of Firefox ..

Is this with all websites/pages, some, a few? Many site issues can be caused by corrupt cookies or cache&#46; '''Warning ! ! ''' This will log you out of sites you're logged in to&#46; You may also lose any settings for that website&#46; * [https://support&#46;mozilla&#46;org/en-US/kb/delete-cookies-remove-info-websites-stored Delete cookies to remove the information websites have stored on your computer] {web link} * [https://support&#46;mozilla&#46;org/en-US/kb/how-clear-firefox-cache How to clear the Firefox cache] {web link} If there is still a problem, '''[https://support&#46;mozilla&#46;org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode]''' {web link}<br> by holding down the '''<Shift> ''(Mac=Options)''''' key, and then starting Firefox&#46; A small dialog should appear&#46; Click '''Start In Safe Mode''' (not Refresh)&#46;<br> Did this help? While you are in safe mode; Try disabling graphics hardware acceleration in Firefox&#46; Since this feature was added to Firefox it has gradually improved but there are still a few glitches&#46; ''[https://support&#46;mozilla&#46;org/en-US/kb/forum-response-disable-hardware-acceleration How to disable Hardware Acceleration]'' {web link}

Thanks, I desactivate the extension "Cookies auto delete" and then it works !

That was very good work&#46; Well Done&#46;<br> Please flag your last post as '''Solved Problem''' as this can help others with similar problems&#46;