The action would require the installation of packages from not authenticated sources

[veggiefish]

I have already tried all the steps in this thread:

http://ubuntuforums.org/showthread.php?t=1626757

But my problem persists.

Has anyone else had this issue? In "details" of the error:

apport-hooks-medibuntu libavcodec-extra-53 libavutil-extra-51

[dino99]

medibuntu is not needed now (dont have it on Precise at all)

[oldos2er]

Run
sudo apt-get install medibuntu-keyring && sudo apt-get update to install Medibuntu's gpg key.

http://medibuntu.org/repository.php

[veggiefish]

Thank you- adding the keyring worked. :)