--enable-gui : This switch tells MPlayer to compile the gui code. --enable-menu : These switches enable the new menu support. It's like an OSD, but you can also run a shell with it. --enable-shared-pp : This enables the building of a shared libpostproc (library for post processing, featuring filters like sharpen). cp etc/codecs.conf /etc/mplayer : This command copies the standard codecs.conf file to the system-wide configuration directory. MPlayer expects this file at startup.