It looks like that.
Ubuntu's mixer applet is a different UI on the old mixer applet in gnome-applets, and not the PulseAudio-powered volume applet now in gnome-media.
In addition to the article being outdated (the treeview with the one-by-one sound event customisation is already gone), it also invents new features such as «the ability to adjust the alert volume on a per-alert basis». God knows where they got that from.
/The guy who did the last gnome-media release