From Amazon:
Dear Customers,
Good news for Prime members. We’ve just completed a deal with PBS to make Prime Instant Video the exclusive subscription home for streaming Downton Abbey‘s Season 3 starting in June, and all new seasons for years to come.
Prior Seasons 1 and 2, already the most popular TV seasons on Prime Instant Video, are available now for catch up viewing—and will also become exclusive to Prime Instant Video later this year.
If you can’t wait until June for Season 3, you can also buy each episode at Amazon Instant Video the day after it airs. And starting now, we’re also making the last three weeks of this season’s episodes available to purchase before they air on TV in the US. When you buy a TV Pass to Downton Abbey‘s Season 3, or if you already have one, you will receive all remaining episodes instantly.