BBC iPlayer content is protected by DRM (digital rights management) and that is what stops you from keeping the content forever or converting to another format. It's not impossible as I have seen stuff online that was ripped from iPlayer but as of yet, I've been unable to do so. :-(
Credits to Paul Battley for his developement of iPlayer downloader. Bear in mind the downloaded content is on par with VCD quality but better than nothing.
Not stealing jake, I have a friend who missed an episode of strictly and she's such a technophobe I figured it would be easier if I put the episode on a CD rather than trying to explain how to use Iplayer. You are correct though I don't normally do this sort of thing.