MPlayer comes as both source and as an rpm. I prefer the source files, so would d/l the mplayer.tar.gz type file, extract it, run ./configure, make and make install.
If you are used to the Synaptic/apt-get way of doing things, I believe there is a version of apt4rpm & synaptic which runs on SuSE. Yep, I'm right - go here
to get apt and then issue an apt-get install synaptic. MPlayer may then be installable that way.