currently get_iplayer simply silently ignores akamai video streams on the livetv channels
these are currently being used by BBC One's live streaming of World Cup matches.
A simple patch to at least output a proper warning when these are found is available here:
This version of get_iplayer has been superseded by someone else's fork. Please grab the latest version from ftp://ftp.infradead.org/pub/get_iplayer/ or check the mailing list for updates (details on the github wiki for this project).
I will submit your patch to the list.