iTunes Replay is the rumored name of the rumored Apple subscription video streaming service rumored to compete with the likes of Netflix. Apple Insider reported on the rumors a while back, and now App Advice hears it might be coming soon.
There's talk you'll be able to stream content purchased as far back as January of 2009. We're not sure what will happen to content purchased before that. There's also talks of certain content only being available for re-downloaded five times. This lines up with Apple traditionally allowing 5 computers to be authorized to play purchased content under one iTunes account. iTunes Replay is basically just an add-on to what Apple is currently offering with re-downloading content via iCloud. It should also be interesting to see if iTunes Match content will be integrated into iTunes Replay. If we can simply stream a lot of our content, it will free up precious storage space on our devices.
iTunes Replay is the name Apple is using internally for the service. It's rumored it will stay the same upon launch but until then, we won't know for sure. We'll have more as it develops.