If you just want to have a uber file share for people, that is easy. Server with enough memory to hold the working set + fast storage to load that into memory as the set changes and somewhere with unrestricted 10G+ connection for cheap and good peering arrangements.
But a stable streaming platform is much more complex.
I would look into the professional video CDN's setup for this purpose if you want to just stream your content to users. There is a huge list of things to consider if you are trying to build a real streaming platform from scratch and have it reliable and stable for users in a geographic region and it is a specific set of skills and knowledge to build up the interconnects to the end user networks with enough bw to handle the bursty nature of video traffic.
Keep in mind that the netflix cache boxes are there to function as a L1 cache of the video for clients of the ISP alone, and the current versions essentially stream to the local ISPs network at 10g+ from memory or NVMe. All the smarts and coordination is handled in other places and specific chunks are handed off to be served by the local cache servers so that Netflix's transit connections are not flooded with traffic. All the other CDNs use a variation on the same strategy and place cache nodes in key areas from a network peering perspective to minimize the costs they pay delivering content.
Some considerations off the top of my head:
- Number of unique content items in library, excluding transcodes for different profiles
- Average and max concurrent users you want to spend $ to support
- Are you working with live or prerecorded content or both?
- Geographic regions you are targeting?
- Do you need to license it differently by region or geo-lock it?
- What client platforms do you want to support?
- Are you using a customized player and have dev staff to build and maintain that?
- Is this a for-profit venture and how are you monetizing it / accounting for the users and content they watch?
- Do you need to worry about Ads?
- Have you transcoded and segmented the content in all the HLS and other profiles?
- Was the source material > 720p? If so 720p and 480p versions may not be enough for your user base.
- Rate at which new material is added to the collection
- Will there be huge spike of users watching the new content when it is added, and then load drops back to near nill?
If you don't know the answers to the above off the top of your head then I would strongly suggest working with a streaming CDN that has all of that figured out for you. They can also give you an idea of the costs you will incur.
