In Rocket.Chat you have the ability to start video and audio conferences.
This is done by using Jitsi Meet through Rocket.Chat.
Starting a Video Conference
To start a video conference you can simply open the channel actions menu (the three dots on the top right) and select Video Chat.
Other users will be able to join via Click to Join! button that is sent as a message on the channel that the conference is being held.
Screen Sharing
You can start screen sharing by selecting Share screen in the jitsi widget.
In Firefox screen sharing works out of the box, but if you are using chrome, please install this extension to be able to screen share.
Source: Voice and Video Conferencing