If the camera icon is visible at the top of your group home screen, anyone can start a session.
Tap on the icon and tap 'Join video room'.
Only group administrators, hosts and moderators have the ability to customise the look of the video room, lock the room, record session and create breakout sessions.
If the camera icon is not visible it means video rooms are not enabled for this group. Only administrators, hosts and moderators have the ability to enable video rooms.