Not sure to understand what you're asking... is it some sort of streaming feature you're suggesting? It is possible to script that using sockets and low packets size. And remember, mIRC is an IRC client :P
I believe they mean using a path such as \\NetBIOS_Name\files\music\blah.mp3
The best way to find out is to try it. I don't believe it was added, because I don't remember seeing it in the versions.txt--I could of course be wrong.
must be the routine used to play mp3's i doubt that it was hand written, rather some mp3 play routine welded in, and it must not deal with netpaths. Bit sad, but liveable i guess.