Originally Posted by Agrouf
Let's suppose your video is named video.iso
su -c "mount -o loop -t iso9660 video.iso /tmp/video"
you can usually omit the -t iso9660 unless it complains about not being able to detect the filesystem.
Alternatively you can use CDEmu (I think it's a taskbar applet) that lets you mount iso's without using the command line.
But, of course if mplayer does that that would be the most convenient option.