Apple coded the ability to stream iTunes purchased TV/Movie out of iOS sometime at some version iOS 8.
I discovered this feature omission in iOS 9 when I started inquiring about this.
This was an undocumented and workaround feature, from iOS 5 to the last last iOS 7 update, to be able to stream iTunes purchased movie/TV content remotely from an external storage device, but Apple closed down, coded out this ability/workaround since, and it seems that Apple is not going to restore this ability anytime soon!
There is no way to do this any longer!
There is NOTHING you can do to get this to work!
This ability is gone!
The only thing you can do is transfer movies from the drive to your iPad to watch the movies off of your iPad, now!
The wireless drive is just a storage vessel, now and not an external streaming device.
I have resorted to stop purchasing any more iTunes movie/TV content and going back to purchasing physical mulitiformat discs of movies/tv show and creating my own digital copies of DVDs that I can use with both my Seagate Wireless portable drives and wireless and lightning connected mobile, portable USB flash memory drives.
I can now directly stream all of my movie/TV content, once again, from external storage devices.
I still own the first generation iPad that still has iOS 5.1.1 that still has this capability. So, I can still stream movies from my Seagate Wireless hard drive to my 2010 iPad 1, but this is my only iPad that still can do this.
If you want Apple to restore this external streaming workaround feature/ability, send feedback here.
iPad Feedback
http://www.apple.com/feedback/ipad.html
Good Luck!