I am not able to install any application via the command line which requires installation from an unauthenticated source. I tried installing recordmydesktop via the Ubuntu Software Centre but when I try to install a message is displayed that it "requires installation from unauthenticated sources". And then when I click "O.K.", nothing happens. Therefore, I had to do it on the command line. This also happens when I get a message from Software Updater that "a new update is there for your system". So, I can't update/upgrade via GUI. I then have to do it via the command line.
I have a related post here. (please don't consider it duplicate as it is not)