Honestly this app has some of the best free content you can find. Also supports Chromecast.

Perfect timing. My mom was just complaining about no Downton Abbey on Android TV.

Is this full episodes?

Only for Americans, unfortunately.. There is a nice Kodi plugin which is a workaround.

APK Mirror: http://www.apkmirror.com/apk/pbs/pbs-pbs/pbs-video-1-2-0-android-apk-download/