I also would like to see a solution to marce_245`s problem.

To add clarity to the question, it`s not about associating the default player. Follow these steps:

1. Open mplayer.
2. In the list of files shown, it only shows the local files. Fair enough, I don`t really want it to walk my entire network searching for files. Press the Open button.
3. Browse to the network share (when it works) and select the file on the network. The path to the file shows in the filename box to the right of the play button (hmm... Ok, this filename doesn`t show up so then still not able to play).
4. Press the play button.
5. File does NOT play.

A similar issue with Quiver Image viewer. I think it`s a maemo problem more than a mplayer issue. The shares need to mounted so that these apps can find them. But the maemo media player and picture viewer can find the files without the mounts.