The point I was trying to make is that WMP12 will use WDS and its associated metadata writing features instead of its own homwgrown library/metadata system. Therefore the problem you are having specifically with WMP not writing metadata to files may go away.And they probably won't bother fixing code in the current WMP that's going to go away in WMP12.
Will Libraries work like Smartfolders on OSX? Saved searches in Vista are horrendously slow and don't work very well. Can I define my own Libraries? I'd like to be able to say "This is a view of all my avi files >20min on all my disks that I haven't seen yet", have this query run locally as well as my WHS shares, and be updated in realtime. And why can't file metadata be attached to every file (for god's sake, NTFS has had ADS forever) instead of the stupid limitation on tagging only certain types of files. If we can tag any file, define custom searches that use that metadata, and compose Libraries out of these searches, then we are very close to the holy grail of WinFS. But I'm almost 100% sure this is not what we'll get.
The point I was trying to make is that WMP12 will use WDS
I remember an older version of media player (7 or 8 I think) had a command in the menu to 'commit' your data to the files, but that disappeared in subsequent versions