Q: Why is MythStream not an official plugin?
That's in the README (see tarball). I don't want to flame here :)
Q: No streams I: MPlayer
You might need to update MPlayer, or add codecs. See runtime requirements.
Q: No streams II: old demo storage
The world of streams is a dynamic one. A stream working today can be nonexistent tomorrow. A stream running smoothly in Europe can be close to unwatchable in Japan. Streams referred to in the demo database may fail, even if I update the storages every week. And I don't. To make MythStream feel alive you have to wake it up. I know a failing demo database is a marketing disaster, but I'm not into marketing.
Ask. Good ideas are valuable. Spread them widely, so all can benefit. If I think your idea is one of those precious ones, I will pay you back by implementing it. If I think it isn't I could be wrong.
Q: How can I add and remove streams in MythStream?
Edit on the fly by pressing key "E" (EDITITEM action). Or use the MythStream setup modules (MythTV menu, setup, setup, media settings...). Or use StreamTuned on another PC.
Q: My stream X runs out of buffer frequently.
Increase the cache parameter at line 289 (v0.17) of player.xml
Q: The mythstream font is too big/too small.
Change the font sizes in stream-ui.xml.
Q: How do I write a parser?
Check example.pl. This file gives the output your script has to provide. Or copy an existing parser and start editing. Here you can find some tips for writing and testing parsers.