Comment 5 for bug 411284

Apparently libavcodec-unstripped-52 is not installable without forcing. It conflicts with a bunch of packages.
This system is fully updated at the time I'm writing this. (Mon Aug 24 18:19:16 GMT 2009)

dschulz@deepthought:~$ LANG=en apt-cache policy libavcodec-unstripped-52
libavcodec-unstripped-52:
  Installed: (none)
  Candidate: 4:0.5+svn20090609-2+unstripped2
  Version table:
     4:0.5+svn20090609-2+unstripped2 0
        500 http://archive.ubuntu.com karmic/multiverse Packages

dschulz@deepthought:~$ LANG=en sudo apt-get install libavcodec-unstripped-52
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  libavutil-unstripped-49 libopenjpeg2
The following packages will be REMOVED:
  devede ffmpeg gstreamer0.10-ffmpeg gstreamer0.10-plugins-bad-multiverse libavcodec52 libavdevice52 libavfilter0 libavformat52 libavutil49 libk3b6-extracodecs
  libmjpegtools-1.9 libpostproc51 libquicktime1 libsox-fmt-ffmpeg libswscale0 libxine1-ffmpeg mencoder mjpegtools motion mplayer mplayer-fonts mplayer-nogui
  vlc vlc-nox vlc-plugin-pulse winff
The following NEW packages will be installed:
  libavcodec-unstripped-52 libavutil-unstripped-49 libopenjpeg2
0 upgraded, 3 newly installed, 26 to remove and 0 not upgraded.
Need to get 4274kB of archives.
After this operation, 63.2MB disk space will be freed.
Do you want to continue [Y/n]? n
Abort.