if u have a site which has for example a link to a pls file and u click on this link, midori opens a window which asks what u want to do with this link, if u press open nothing happens (at least with flwm).
To assign an application to this mime type do the followings:
install xdg-utils.tcz and Xorg-7.4.tcz (this has xprop inside which is required by xdg-mime)
xdg-mime default smplayer.desktop audio/x-scpls
after doing this midori will open .pls links with smplayer
PS Xorg doesn't need 2 be running