Togetherly - Watch Youtube with friends
DUSK - Anonymous live video
ShareTube - Watch YouTube, synced with friends.
Periscope on Twitter for iOS - Stream live video inside your tweets
Showgoers - Showgoers is a website dedicated to watching Netflix movies together with friends or loved ones who are not sitting on the same PC.
Live Video On Tumblr - Tumblr's answer to Periscope, Facebook Live and Twitch