OpenSolaris Codec Pack includes most of the software you would need to play (and eventually RIP or re-encode) the most spread media content formats on a OpenSolaris machine. Tnx to Alvaro Lopez now it is very easy.

The only thing you have

to do to install it is to execute the following command from a terminal (as root). Binaries are for both i386 and Sparc. The script will detect the platform and install the proper package set:

wget -O - http://opensolaris.es/codec-pack.sh | bash