If you have problems regarding flash sites, eg: if you are watching a flash video online on some website like you-friggin-tube and you want to play Rhythmbox, Amarok or your player of choice in the background but you cant because you can only hear one or the other, here is what you are going to do to fix it,
install libflashsupport … problem solved … or at least it was for me!
sudo apt-get install libflashsupport
ok i jumped the gun abit on this it didnt quite fix my problme … well it did but it caused Firefox to crash constantly when loading a flash site ….
so upon my research i found this tutorial HOWTO: PulseAudio Fixes now i like to write my own tutorials … but this guy knows his crap and this was too much for my limited knowlege in linux … so go to his post and follow it .. it will solve you problems =P