Using Firefox1.0 (with gecko-sdk-i686-pc-linux-gnu) and MPlayer-20041208 and mplayerplug-in CVS (ChangeLog 12/04/04), MPlayer extra codecs "all-20041107," live.2004.12.07: I keep running into "rtsp is not a registered protocol" for some streams.
Here is the latest (which works fine in standalone MPlayer):
(There are several stream choices, they all get the same error with the plugin.)
The above does not take you to the exact page, this should:
If not, here is a specific link from the page:
To correct this issue, custom protocol handlers will have to be written. I have looked into it, but have not started on it and do not have a time frame if or when I'll start on this.