mplayer and apt-get
 

Last night when I was fixing old but new to me laptop I installed apt4suse. I am running suse9.3 and everything installed and setup without any errors. I got the new firefox but when I did mplayer it said that it was not found. I checked to see if I was typing in the wrong package. I tried apt-get install mplayer, apt-get install mplayer-suite.

Don't know much about apt4suse, but my first thought is that you're missing some repository that would have mplayer in it. Maybe try posting a source list. For ubunntu (debian apt) it's in /etc/apt/sources.lst