The gnome keyring issue can safely be ignored .. indeed it *needs* to be ignored in Peppermint.
To stop anything running in the terminal - Ctrl+C = Cancel
There used to be a couple of GUI wrappers for get_iplayer .. but they don't seem to have been updated in years, and don't work any more.
I'll keep looking for one though.
That said, the command line version isn't "that" hard to use.....