1. You need to have a complete copy of the collection _somewhere_ but P2P only benefits you if most requests can be served from copies close to the viewer. That's a problem if you have a large collection with a long tail (which is true in most cases).
2. P2P requires a fair amount of over-provisioning because most users don't have high uplink capacity, especially if you're avoiding the congestion which will cause people to stop using the service.
3. P2P nodes are unreliable & have limited capacity so you maintain a large list and update it frequently. For a popular movie, that's probably going to work out okay since most people will leave the player open for a couple of hours but for shorter or less popular content that's likely to mean that a lot of traffic is going back to the seed servers or ends up being slower going to that one guy in Moldova hosting some obscure video.
Consider how the open-source community has no legal considerations but most downloads of Linux ISOs, packages, etc. use HTTP from CDNs or mirrors because it's faster and more reliable. This problem is not impossible to solve but there's more to it than copyright and other legal considerations.
Comments
There are some non-trivial technical problems:
1. You need to have a complete copy of the collection _somewhere_ but P2P only benefits you if most requests can be served from copies close to the viewer. That's a problem if you have a large collection with a long tail (which is true in most cases).
2. P2P requires a fair amount of over-provisioning because most users don't have high uplink capacity, especially if you're avoiding the congestion which will cause people to stop using the service.
3. P2P nodes are unreliable & have limited capacity so you maintain a large list and update it frequently. For a popular movie, that's probably going to work out okay since most people will leave the player open for a couple of hours but for shorter or less popular content that's likely to mean that a lot of traffic is going back to the seed servers or ends up being slower going to that one guy in Moldova hosting some obscure video.
Consider how the open-source community has no legal considerations but most downloads of Linux ISOs, packages, etc. use HTTP from CDNs or mirrors because it's faster and more reliable. This problem is not impossible to solve but there's more to it than copyright and other legal considerations.