Watch2Gether - Watch2Gether is an app that allows multiple people to watch the same content simultaneously and interact with each other while watching.
Spatial - Collaborate from anywhere in AR
Metastream - Watch streaming media with friends
VRChat - Create and play in virtual worlds with others
StreamParty - StreamParty is a watch communiry, that allows you to watch video streams in sync with the people you care about, on multiple services.
VeeR VR - Global VR video community