CoWatch

For those familiar with WebRTC, CoWatch allows you to watch video files with your friends online just from within your chrome browser using WebRTC.

This is how it works:

You create a room with a shareable link.
You or a member of the room opens a video file in the room.
The Video/Audio is streamed to the others in the room using WebRTC.
Source

The video is automatically available to all members of the room immediately you share the link after uploading the video of your choice. Friends you’ve invited can now watch with you.

NB: It’s only available on chrome browser as of now.

You can try it out too