iTunes U - Subtitle not working on "Coding Together: Developing Apps for iPhone and iPad (Winter 2013)"

I'm following "Coding Together: Developing Apps for iPhone and iPad (Winter 2013)" and when I tried to watch on iPad I could not enable subtitle, but in the last "season" closed caption works fine.

I'm not sure, but I believe that the issue is with the kind of subtitle: This season is with 3GPP subtitle and the old one was Closed Caption.

The point is: Why does iTunes U don't use the infrastructure of the video player?

Best Regards

Taka