You can install mplayer in FC4 using yum. Start here,
http://rpm.greysector.net/mplayer/yum.html. Follow the link to set up your yum configuration to use the repository with mplayer.
Once you've set up yum to use the appropriate repository, do this:
- Open a terminal.
- Log in as root.
- Type yum install mplayer or yum install mplayer-gui
That should pretty much do it. Unless, of course, you're bent on installing it from source.