I don't want to send you on a wild goose chase, but for what it's worth, I usually install mplayer and ffmpeg (the latter more for transcoding) and it seems that that usually pulls in everything I need. On occasion, I'll need to get libdvdcss
http://packages.atrpms.net/dist/f16/libdvdcss/
from atrpms--although that's for F16, it will probably work. (I haven't had to install it on any F17 installs, so not 100 percent sure about that.)
Those are about the only hints I can think of....and I make no guarantees, usually just installing vlc pulls in all necessary codecs.
One other possibility, though probably a waste of time is to uninstall then reinstall vlc.