I use Ubuntu 10.04.
Ever since I updated gstreamer, Movie Player doesn't work properly anymore and neither does Rhythmbox.
How can I keep using the previous version of gstreamer that worked?
To downgrade a package go to Synaptic Package Manager. Find which package you want to downgrade. Select it. Then in the menu, go to Package -> Force Version...
Then you would be able to select which version.
You can also do it in cli, for example:
sudo apt-cache showpkg gstreamer0.10-pulseaudio
It will show the depencies and after Provides will show the versions: 0.10.21-1ubuntu3 - gstreamer0.10-audiosource gstreamer0.10-audiosink 0.10.21-1ubuntu2 - gstreamer0.10-audiosource gstreamer0.10-audiosink
Then you can downgrade: sudo apt-get install gstreamer0.10-pulseaudio=0.10.21-1ubuntu2