I wanted to let everyone know that amazon prime video is now offering audio description. I saw this come across on my twitter feed from ACB National. Here is a link to the ACB's announcement:
I have tried it on one of the series mentioned in the list and it does work. It looks like it works similar to NetFlix. Once you get a show started, you need to find the autdio options and check english with audio description. Everyone who has access to prime video go and have a look.