If you have a bad network, you can be put into the audio fallback mode, which hides the video and keeps the call going in audio mode. In such circumstances, a warning indicator appears on your tile, indicating audio fallback mode, which can be hovered over to reveal further information about the error. You may always move to a better network to get the video back, or if you have a decent network, the video will stream back. This alert remains till the network is weak and then fades away when the network improves.
