OK. So for anyone else having this issue, when Adobe decides to piss on us Linux Flash developers again:
This time it was making my Flex Builder Alpha expire. First it took hours ( and two unhelpful Adobe reps ) to realize that there was a new alpha available for Flex. I thought they were trying to make me buy a license. So I figured, oh, cool, it'll be a cinch to upgrade. But I was incorrect.

Upgrading Flex builder linux to alpha 5, on 64-bit Ubuntu 9.10:

So I've been doing more Flex / red5 development recently and have been increasingly frustrated by the tendency of Flash 10 to often crash and burn when I try to access my webcam. To my amazement, there's an easy fix - just run firefox with

Running Ubuntu 64-bit and trying to record audio with flash?

There's a quick solution- get a newer version of the flash player...Just run this to remove your existing flashplayer package, get a new copy of the flash player, and move it to the mozilla plugins directory.

My microphone worked like a charm after this. Enjoy!

sudo apt-get remove flashplugin-nonfree;
wget -c http://download.macromedia.com/pub/labs/flashplayer10/libflashplayer-10....
tar -zxvf libflashplayer-10.0.d21.1.linux-x86_64.so.tar.gz;