Jamawkinaw Enterprises has released Downcast 1.0.11, which adds an option to switch to audio-only playback of video podcasts. Selecting this option in the video context menu closes the video but continues playing the audio. The podcatcher app also squashes a bug that caused file extensions to be dropped for imported episodes, fixes priority play for playlists, ensures that statistics for partially played episodes are properly refreshed, fixes a problem that prevented the selected podcast/playlist from being reselected after a restart, and fixes multiple bugs that could cause crashes. ($9.99 new from the Mac App Store, free update, 6.4 MB, release notes)
View Extra Audio Details in Snow Leopard
In Snow Leopard, Option-clicking the Volume icon in the menu bar displays a list of sound input and output devices. Choose one to switch to it; it's much easier than using the Sound preference pane. Also, hold Shift and click the icon to set the system volume, which is separate from the general output volume.