westor: In Vista+, the Windows system has control over individual application's volume. Adjusting the volume of another application is a matter of a system API call, the same one that mIRC uses to change wave/midi volume.
I couldn't say if mIRC would require administrator rights to tinker with the volume for Flashplayer.exe or Firefox.exe
Newbie: There are other Windows scripting languages out there that can, including AutoHotkey, if it's something that doesn't necessarily have to be performed by mIRC script.
Oh yeah, I know there are other languages the thing I really don't know is how to implement them with mirc. For example, I'm trying to make a web page using html and java script which plays a youtube video and then refreshes to play another youtube video in the process. I'm assuming that I could alter the volume using java script my question would be how could I manipulate that using my mirc bot?