With much thanks to this blog post, which reveals how to fix /etc/ushare.conf and /etc/init.d/ushare.
Install the dependencies:
$ sudo apt-get install libupnp-dev pkg-config $ sudo echo "deb http://www.geexbox.org/debian/ unstable main" >> /etc/apt/sources.list $ sudo apt-get install libdlna-dev ushare
(uShare’s being installed here just to grab the conf files.)
Pick up the latest version of uShare (assuming Mercurial is installed):
$ hg clone http://hg.geexbox.org/ushare
In the uShare directory:
$ ./configure --prefix=/usr/local $ make $ sudo make install
Now the configuration files need to be edited. Make the appropriate changes to /etc/ushare.conf, making sure to modify ENABLE_XBOX to USHARE_ENABLE_XBOX. The rest should be self-explanatory.
In /etc/init.d/ushare, add USHARE_OPTIONS="-f $CONFIGFILE" so that the correct command line is sent to uShare.
And now you should be able to stream videos from your Ubuntu fileserver to your Xbox 360.