If you have VOD’s set up (i.e. recordings, uploaded videos), traffic will be consumed every time one of your viewers is watching any of those. To save on that you can download and delete your recordings, then take them to youtube or someplace else
Also, there is some residual (very little) bandwidth consumption when one/some of your channels are still active (but not broadcast to); this is due to i.e. viewers trying to access your channel and receiving a “not found” message VOD stands for video on demand fyi.
Indeed, there will be a “Stop” or “Turn off” button soon. To reassure, there is bandwidth consumption, yet in the range of a few megabytes, before the channel turns off by itself after about 45 minutes of inactivity (i.e. no streaming)