I have no flash-player-plugin sound

in Firefox of pclinuxos-kde-2012.08+all updates.
Tested with this Youtube
.
A complete uninstall > install of the package does not change this situation.
The 00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller of the on-board
P5QLD PRO with the snd_hda_intel(ALSA) driver is used.
In configuration center 'PulseAudio enabled' and 'Use Clitch-Free mode' are marked.
In KMix (HDA Intel) Master/Front/Surround/Center/LFE/PCM/CD/Side are all at maximum.
With the same hardware and settings it's no problem in Mageia2.
Anybody any idea how to solve this problem
