iTunes U videos not working (No Video Streaming working on iPad)

I have iPad third generation and I connect to internet through an entreprise network. The problem is that no video streaming or video downloading happens on my iPad, this is also the case with iphones or other iOS devices.

The network has blocked everything but has exceptions for things needed like browsing.

FTP, P2P are some of the many things that are blocked. All kinds of video streaming for pc's is blocked before 6 PM. Youtube, vimeo for pc's only work after 6 PM.

But on iOS devices even after 6 PM youtube app, vimeo on website, ted videos, AND ESPECIALLY ITUNES U dont work. They all open but give error when a video is clicked. App store is working though.

I talked with the network administrators and many ports were checked and tested but still the videos did not work. These same work in direct personal broadband connections so there is no problem with the devices.

PLEASE TELL WHICH PORTS OR THINGS SHOULD BE UNBLOCKED SO THE videos WORK.