3G unrestrictor wont work for the BBC Iplayer.
I dont think there's a way to have this done at the moment.
From the Dev's site:
"◦BBC iPlayer
I tried to get it to work too, but it seems that the iPlayer uses a system that detects whether an IP-Address belongs to a mobile internet provider and then blocks it if the mobile, iPhone version of the iPlayer is used. This is possible, because the iPlayer uses the service of a company at which every internet provider has to register it's IP-Ranges. Since the check whether a mobile internet connection is used is made on the iPlayer side and not on the iPhone's side in the Safari app, I cannot unrestrict that.