Just to be clear, you can avoid a LOT of problems and cost by just using
modelcentro.
When running a membership site, you have things to deal with.
1. Password sharing (this is a huge problem).
2. Having a dedicated server. If you are going to use 4k vids, these are HUGE files. It means ten films that are 30 mins long will need a lot of disk space. I presume you will need a dedicated server. One that will not crash if you get more than ten people on your site.
3. Piracy. Do you let people download and save films or watch online only.
4. Affiliates.
5. Payment.
6. The website