For example if I have both my speakers and headphones plugged in I might want to have a YouTube video playing over my speakers but all other sound playing from my headphones.
Changing it so that Flash outputs to the Speakers device and having the default audio device as Headphones would work perfect.

But Flash doesn't seem to support changing the audio device, so I can't do that, and Windows 7 has no built-in function to change it for that program only either.
I have tried a program called IndieVolume which seemed to be the perfect solution, but it doesn't work in Windows 7 64-bit.
I also tried a program called Vista Audio Changer but that changes the audio output for all devices at the same time when the chosen program opens/closes.
I even tried running the web browser sandboxed and changing the Windows default audio output device inside the sandbox, but that changed it for the un-sandboxed programs too.

I can't seem to find a program or another solution to fix this mess, does anyone know of a program that allows you to change the audio playback device for a specific program?