[email protected]:/home/neztiti# sudo apt-get build-dep xine-ui
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to find a source package for xine-ui
[email protected]:/home/neztiti# sudo apt-get install xine-ui
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

Since you only requested a single operation it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
  xine-ui: Depends: libxine-main1 (>= 1.1.1) but it is not going to be installed
E: Broken packages

sudo su -
echo "deb http://zap.tartarus.org/~ds/debian unstable main contrib non-free" >  /etc/apt/sources.list.d/tartarus.list
echo "deb-src http://zap.tartarus.org/~ds/debian unstable main contrib non-free" >> /etc/apt/sources.list.d/tartarus.list
aptitude update
aptitude install libxine1 libxine1-ffmpeg libxine1-vdr xine-ui