Pois é, também tive problemas pro Ubuntu instalar automaticamente os pacotes gstreamer.
E quando tento fazer isso pelo temrinal, ele simplesmente não consegue localizar os pacotes.
Seria algum problema da minha source list?
# Automatically generated sources.list
#
http://www.ubuntu-nl.org/source-o-matic/#
# If you get GPG errors with this sources.list, locate the GPG key in this file
# and run these commands (where KEY is replaced with that key)
#
# gpg --keyserver hkp://subkeys.pgp.net --recv-keys KEY
# gpg --export --armor KEY | sudo apt-key add -
#
# If you don't know what to do with this file, read
#
https://help.ubuntu.com/community/Repositories/CommandLine# Ubuntu supported packages
# GPG key: 437D05B5
deb
http://br.archive.ubuntu.com/ubuntu feisty main restricted
deb
http://br.archive.ubuntu.com/ubuntu feisty-updates main restricted
deb
http://security.ubuntu.com/ubuntu feisty-security main restricted
# Ubuntu community supported packages
# GPG key: 437D05B5
deb
http://br.archive.ubuntu.com/ubuntu feisty universe multiverse
deb
http://br.archive.ubuntu.com/ubuntu feisty-updates universe multiverse
deb
http://security.ubuntu.com/ubuntu feisty-security universe multiverse
## PLF REPOSITORY (Unsupported. May contain illegal packages. Use at own risk.)
## Medibuntu - Ubuntu 7.04 "feisty fawn"
## Please report any bug on
https://launchpad.net/products/medibuntu/+bugsdeb
http://medibuntu.sos-sts.com/repo/ feisty free non-free
#deb-src
http://medibuntu.sos-sts.com/repo/ feisty free non-free
## CANONICAL COMMERCIAL REPOSITORY (Hosted on Canonical servers, not Ubuntu
## servers. RealPlayer10, Opera, DesktopSecure and more to come.)
deb
http://archive.canonical.com/ubuntu feisty-commercial main
## enlightenment e17 beta, use at your own risk
## E17 is in Beta and may break or break your system
deb
http://edevelop.org/pkg-e/ubuntu feisty e17
deb
http://e17.dunnewind.net/ubuntu feisty e17
deb-src
http://edevelop.org/pkg-e/ubuntu feisty e17