spoilr.tv is to something like that, but asynchronously. Your buddy is a week behind on Game of Thrones, but still sees your comments on the last episode, time-

spoilr.tv is to something like that, but asynchronously. Your buddy is a week behind on Game of Thrones, but still sees your comments on the last episode, time-synced with his watching it (and you're going to be notified if he/she responds to them).