I just downloaded and tried to run the new LinuxMCE video and once again had
difficulty with this format.  Here is the msg I get:

The filename "LinuxMCE_0704_Demo_Video_2mbit.ogm" indicates that this file
> is of type "OGM video". The contents of the file indicate that the file is
> of type "Ogg Theora video". If you open this file, the file might present a
> security risk to your system.
>
> Do not open the file unless you created the file yourself, or received the
> file from a trusted source. To open the file, rename the file to the correct
> extension for "Ogg Theora video", then open the file normally.
> Alternatively, use the Open With menu to choose a specific application for
> the file.
>

I've tried opening it with Movie Player, MPlayer Movie Player, and vlc to no
avail.  The above message is from using the Movie Player default under
Ubuntu 7.04.  Although the message seems to say I could rename the file to
use an Ogg Tjheora extension, there is no indication what that would be.
Besides, although linux now does pay some attention to file extents for file
types, one does not expect that to be the default behavior.

Any ideas?
-- 
The nice part about being a pessimist is that you are constantly being
either proven right or pleasantly surprised.
  - George F. Will