depois de concordar em baixar e instalar plug-ins extras de multimídia,
diz que a dependência do pacote não pode ser resolvida, com o erro abaixo:
The following packages have unmet dependencies:
gstreamer0.10-plugins-bad:i386:
Depends: libc6 (>= 2.15) but 2.15-0ubuntu20 is to be installed
Depends: libcairo2 (>= 1.2.4) but 1.12.3+git20120608.f228769d-0ubuntu0ricotz~quantal0 is to be installed
Depends: libcdaudio1 (>= 0.99.12p2) but 0.99.12p2-12 is to be installed
Depends: libcurl3-gnutls (>= 7.16.2) but 7.27.0-1ubuntu1 is to be installed
Depends: libdvdnav4 (>= 4.2.0+20120524) but 4.2.0+20120524-2 is to be installed
Depends: libfaad2 (>= 2.7) but 2.7-8 is to be installed
Depends: libgcc1 (>= 1:4.1.1) but 1:4.7.2-2ubuntu1 is to be installed
Depends: libglib2.0-0 (>= 2.31.8) but 2.34.0-1ubuntu1 is to be installed
Depends: libgsm1 (>= 1.0.13) but 1.0.13-4 is to be installed
Depends: libgstreamer-plugins-bad0.10-0 (= 0.10.23-7ubuntu1) but 0.10.23-7ubuntu1 is to be installed
Depends: libgstreamer-plugins-base0.10-0 (>= 0.10.36) but 0.10.36-1ubuntu1 is to be installed
Depends: libgstreamer0.10-0 (>= 0.10.36) but 0.10.36-1ubuntu2 is to be installed
Depends: libmpcdec6 (>= 1:0.1~r435) but 2:0.1~r459-1ubuntu1 is to be installed
Depends: libopenal1 (>= 1:1.13) but 1:1.14-4ubuntu1 is to be installed
Depends: liborc-0.4-0 (>= 1:0.4.16) but 1:0.4.16-2 is to be installed
Depends: libpng12-0 (>= 1.2.13-4) but 1.2.49-1ubuntu1 is to be installed
Depends: librsvg2-2 (>= 2.14.4) but 2.36.3-0ubuntu1 is to be installed
Depends: librtmp0 (>= 2.3) but 2.4+20111222.git4e06e21-1 is to be installed
Depends: libschroedinger-1.0-0 (>= 1.0.9) but 1.0.11-2 is to be installed
Depends: libsndfile1 (>= 1.0.20) but 1.0.25-5 is to be installed
Depends: libssl1.0.0 (>= 1.0.0) but 1.0.1c-3ubuntu2 is to be installed
Depends: libstdc++6 (>= 4.1.1) but 4.7.2-2ubuntu1 is to be installed
Depends: libvpx1 (>= 1.0.0) but 1.1.0-1 is to be installed
Depends: libxvidcore4 (>= 1.2.2) but 2:1.3.2-9 is to be installed
Eu tive o problema semelhante.
Eu resolvi isso indo ao Ubuntu Software Center e instalando os seguintes pacotes:
GStreamer extra plugins
GStreamer ffmpeg video plugin
GStreamer plugins for mms, wavpack,qucktime,musepack
Depois de instalar todos esses pacotes, eu pude reproduzir vídeo sem problemas.
Tanto quanto eu entendo o sistema deve ser capaz de instalar os pacotes dependentes por si só, mas há um bug