I would look at this angle from three angles:
1. What price do we need to have to be competitive with other market offers (Netflix, Hulu, etc)
2. What value do our customers see in our product and what is their willingness to pay (consumer research driven approach)
3. Cost-based approach (what is the cost of buying the content, operating the platform, and buying CDN capacity, marketing, etc.)
Having previously built a similar product before in my career your pricing decision, in this case, will be very much driven by competitive pressure as pretty much everyone is trying to catch up with Netflix and offer a differentiated product vs them.