I'm using Arch Linux x86_64 with Gnome and PulseAudio. I have USB speakers, which work for the sounds in system menus and most other applications. But whenever I play Flash videos, they output their sound through the onboard sound card (which usually isn't hooked up to anything). This happens in both Firefox and Chromium. I can't find anything that would let me redirect Flash's audio output to my USB speakers.
The following relevant packages are installed:
gnome-media-pulse
gnome-settings-daemon-pulse
libcanberra-pulse
pavucontrol
pulseaudio
pulseaudio-alsa
lib32-libcanberra-pulse
lib32-libpulse
flashplugin