A couple of nights ago, the flash plugin crashed yet again on me, and I decided to look into it. Here's the details of what I found, in the hopes that it may help others. This is a bit Ubuntu specific, but the information might be useful to those running other distributions.
I found ubuntu bug https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/192888 which describes what is happening in great detail.
For those that don't want to click on the link, the short of it is that the flash player has an interface so that you can write an library to make it support audio output libraries that it doesn't natively support. There is a bug in the flash player that makes the player very unstable when this interface is used. Modern Linuxes all tend to use this interface to support modern sound servers, since flashplayer doesn't have any support for sound services.
Apparently, flashplayer 10 does support the sound correctly, so I ended up following the instructions here: http://ubuntuforums.org/showpost.php?p=5587712&postcount=472 and that seems to work. We'll see how my milage fares.
Note that I tried installing the flashplayer manually from here: http://labs.adobe.com/downloads/flashplayer10.html. But I couldn't get the sound to work, so there is still something wrong with ubuntu's sound packages, and one really does need the backported packages from Intrepid to get player 10 to work.
For those of you not on Ubuntu, you can try removing libflashsupport and installing flash player 10, as that might work just fine for you.
This link here: http://ubuntuforums.org/showthread.php?p=4928900 is the manual steps that one can do to get the Ubuntu audio configuration to be sane (and also has instructions on how to install a wrapper for mozilla plugins so that when they crash, they don't take down the browser), but I couldn't get everything to work right with player 10 with those instructions, and I then noticed the link at the top which redirected me to the other forum post that I mentioned earlier.
Phew. Hope this helps.