I'm having difficulty getting my USB mic to work in Flash. It works fine in Audacity and Skype, and I can hear sound in Flash, but it won't record (for YouTube and BlogTV).

I'm running Chakra, sound card is built onto the motherboard (nVidia MCP51), microphone is a Behringer C1-U.

To be honest, I don't even know where to start - is it an ALSA issue, a KDE issue, a Flash issue? Any advice would be greatly appreciated.

Flash (judging by it's handling of output devices prior to Pulseaudio) is probably trying to open a hardcoded /dev/ device which either is the wrong one, or doesn't exist. Try running strace or lsof over Flash/Your Browser.