Grayed out packages mean that Update Manager is not able to updateinstall them automatically due to somean issue.
The issues are typically to do with resolving dependencies and conflicts. Try manually installing them through the Synaptic Package Manager or apt-get. That should throw up the error that causes Update Manager to not install these packages.
$sudo apt-get install gstreamer0.10-plugins-bad
A typical scenario in which this could happen is if you have included in your sources a PPA that is pushing this package, but not some packages that this depends on.