... i just erased my question when i realized it can be resolved if there's a media player out there that can play silverlight and change the audio output (like vlc, but vlc doesn't support silverlight).
(edit:... my kid watches either youtube or netflix through monitors (speakers), i'd like to run everything else through my headphones, using the routing mixer program totalmix that comes with my rme babyface. what would be really handy would be a browser that allows you to change the audio output of the different tabs, let alone the browser itself, which NONE do, after extensive research. how hard is it. ... or if flash or silverlight allowed different audio outputs. it seems such a basic simple function that every other program ever created has built into it, except for browsers, which is probably the most used type of program in the world.)