Over at the forum there's a thread on it. iplayer basically uses flash which is no good for the PCH. It then started using mp4 for certain devices such as the iphone. iplayer has to detect your device as such a device and then start the relevant stream flash or mp4. mp4 is fine for the PCH. I can see it been setup by Syabas as there servers are based outside of the iplayer allowed area.
Search at networkmediatank forum for iplayer and you will see how the discussion has developed over time as has iplayer. A current decision has not been given but for reasons above dont think it will ever work. See if you can get the firefox trick working if that doesnt work any longer there's no chance.