Here's a question, why can't I just use charcoalgray's webinterface stuff right on my PC?

Because Charcoalgray's web interface depends on the Hijack web server code to feed it the playlist data, it doesn't compile that itself.

How Hijack gets that data, I'm not sure. I don't think it tries to index the FIDs in real time, although I suppose that's possible since instantaneous response isn't necessary for the web interface. And I can't imagine that it loads its own copy of the player's database into memory, so maybe it peeks at the existing player database in memory? I dunno. Mark, how does it do this nifty trick?

In any case, if you wanted to write your own on-the-PC interface for playing raw FIDs, it's pretty do-able, you just have to be able to parse and index the FIDs yourself. Or, figure out the player's database format and copy the database onto your PC in addition to the FIDs and use it as your source.