Full-screens the Webcam selection window.
If you would still like the guest to have access to the screen-sharing button once they have joined the call, you can force it to appear with the
&ssb option. The
&webcam option by default will hide the screen-share button otherwise.
Starting with v19 of VDO.Ninja, there is also the
&webcam2 option; a minor UI variant that requires an additional button press, but more clearly preps the guest to the fact they will be sharing their webcam.