The constantly-changing XOR encryption on the iPlayer downloads turned out to be a red herring. The Beebhack team—it’s definitely a team effort now—has been hard at work finding the real secret that lets the iPhone download working video. And, as of last night, it’s been cracked. Downloads are back!
Getting hold of a couple of session traces really made it happen. The details are on the wiki.
I’ve implemented the new discoveries and updated the tarball and GUI.
As a side-effect, you can no longer resume a partial download. But hey—due to the unique way in which the BBC is funded (or, rather, peered), that bandwidth is not their problem.