Theater Mode
Riot Games Support on Twitter
Not sure if I didn't scroll far enough to see of this had already been brought up, however there is now a section on your play profile for "Highlights". Any saved snippet from a downloaded game replay will automatically be stored in here.
How about creating a game mode where you can view these highlights, or perhaps even whole games as a group? The party leader selects the video, creates the lobby and controls the.. controls...
Anyone in the lobby can chat (or use voip) and when that game is finished they see the post match screen or just get sent back to the lobby.
Thoughts?