It's tremendous that (as far as I can tell) this has all been architected and developed internally at the BBC. So refreshing in the current climate of public entities outsourcing everything. Much better value for money - and more to the point demonstrates that complex projects can be successfully completed internally.
I'd be interested to hear why they chose PHP. (It's not exactly the framework-du-jour, so they must have positively chosen it).<p>Also, it seems to me that the web page serving would be the most trivial part of iPlayer. Scaling the video and recommendation database is probably a more interesting topic.
Ironic that this returned the following error when I tried to read it: "Error 500 - Internal Error. This might be because: We are experiencing abnormal traffic to our network." :-)