Why are certain episodes of Ancient Aliens History Channel now being charged for and others are not?

Hello. Individual TV episodes are available for purchase. You can purchase select seasons of some TV shows, which include all episodes from that season at a discounted rate compared to buying individual episodes. The prices and availability of content are set by the programmer. Certain seasons and or episodes can be available and others may not be. Hope that helps clear this up. If there is anything else we can assist with, please let us know. Thank you!
-Julian

The quick answer, it's and History Channel charging you. Cox doesn't make that decision, they have to comply with the broadcaster.