You could maybe find rpm's at
www.rpmfind.com or
www.rpmseek.com, but they usually don't work right and are a pain with dependencies. Your best shot will be compiling from source. If you follow the read me at mplayer page, most likely will compile without a problem (I've compiled on Redhat 7.3, 9.0, Mandrake 9.0 and Slackware 9.0 without problems).
Good luck!