Netflix Party - Netflix Party is an extension for watching Netflix remotely with friends and family for movies nights with that long-distance special someone.
Hyperbeam - A better way to watch together online
Watch2Gether - Watch2Gether is an app that allows multiple people to watch the same content simultaneously and interact with each other while watching.
Metastream - Watch streaming media with friends
Vemos - Virtual movie nights made easy on Netflix, Prime and more
ShareTube - Watch YouTube, synced with friends.