Eventually, I managed to get the videos that I downloaded with cuteTube and get_iplayer working by using KMplayer + mplayer. MPlayer cannot be hw accellerated at the moment so initialise the playback then quickly press pause to locally cache. A glossy 360p, which looks "ok" (good but not amazing) on a 42"; importantly, no jumping though. Going over 360p (approx 500kbps) does cause jumping and sound to de-synchronise when video isn't h/w accellerated.

Bit off topic but I am currently working on a simple get_iplayer webpage-UI (js & ht/x-ml) but got to brush up on my cgi-scripting to actually retrieve the content. Nothing to compare with qml-/cute-Tube but better than trying to remember all the flags and settings for get_iplayer!

Edit:
Thanks for looking into this. The good news, I suppose, is that a download client does exist for iPlayer: However its commands are quite difficult to manage/remeber hence the need for a more user friendly client. As mentioned above, I had trouble playing iPlayer video with nokiaplayer but mplayer works ok - guess it's the way each accesses/uses the codecs.