i've always got it working by this way:
1) as root, make a directory in /usr/lib called win32, i.e. /usr/lib/win32.
2) go to the mplayer homepage, then download all the codecs, then extract them into the /usr/lib/win32 folder. make sure the "recreate folders" option is not checked when you extract! mplayer won't be able to find the codecs if you do.
3) go to freshrpms.net, get "apt for redhat 9," and "synaptic," then install them.
you'll now be able to install mplayer with apt, and everything will be configured for you. you can also get totem this way, which i prefer over mplayer, but that's a personal preference. i have them both installed.
I'd rather have a bottle in front of me than a frontal lobotomy.
AMD Athlon 64 3000+ | MSI K8T-NEO FSR | 2 X 512MB Kingston Hyper-X PC4000 | BFG 6800/OC 128 DDR | Samsung SP1213C 120GB SATA | Lite-on LDW-411S 4X DVD +/- RW | Aspire 550W PSU