Not sure. I think I’ve seen some trailers, or free content. Mostly I use YouTube, along with Amazon Prime.
http://www.google.com/search?q=curiosity+stream&tbm=vid
yeah...I have found
YouTube to be food for short documentaries. but the get exhausted easily.
That's my lineup, too. Although I did add KLOWD TV when they offered One America News free through Dec. 31! And it really is free!