Downton Abbey Season Purchase Debacle

previous seasons. downloaded easily, watched easily.

Season 4, not so much. unable to watch in itunes or video on ipad.

Seems individual episodes are now "original UK version", so something has changed.

Video stops and starts and doesn't play. Paid just under $20., for something can't download and can't watch.

Keeps giving me a message to check storage. Plenty of storage.

Is there a secret I'm missing?

Thx for help or suggestion!