I'm quite sure that the exact thing you want to do would not worth the hassle.
However, as sounds are usually related to a single app why would not you write a script for just that application to turn off power savings while you keep it running?
(example is for VLC)
/usr/bin/xset -dpms &
/usr/bin/xset s off &
/usr/bin/xset s on
Or you could just turn the 3 settings off that affect the display: "Dim Display" and "Screen Energy Saving" (in system settings->power management) and "Screen Saver" (in system settings->display and monitor).
But to run a background process to address the incompleteness of the power management daemon? Come on...
By the way this "feature" is present at least since Lucid (10.04, 29/04/2010). It is still present in Trusty (14.04) as of 25/01/2014, I tested it. How embarrassing would that be for me if I was an Ubuntu developer?