Hi Ernst,
Sorry to hear you're having troubles.
If you're having troubles with both YouTube and CB, the chances are good that it's nothing wrong with either of the sites. More likely, it's something to do with your browser settings perhaps or a conflicting plugin.
If you click the audio player to play and the time counter's going, the plugin is working fine. Make sure the volume slider beside the counter is up full too. Then look at the volume sliders for windows and your other audio devices in the chain.
If all of those are fine, you may have to think back to see if you installed a plugin or made any other change to your browser 1-3 weeks ago that might coincide with these issues?