The service allows Facebook Messenger users to add live video right into any Messenger chat, the company said in a Facebook post:
Instant Video makes live video with your friends as easy as sending a sticker or emoji. Here’s how it works: When you and a friend are viewing your conversation at the same time, the video button in the navigation bar will pulse. Tap the pulsing button to instantly start the video stream and share your experiences in real time. Your video will be viewable over the text conversation. Your friend can watch the live video or choose to share a video back.