call.remoteVideo contains the HTML5 <video> object used to show images received during a call. The image of the person you are talking to.
If the HTML5 <video> object you intend to use has id="remoteVideo" you do not need to set call.remoteVideo, only if the <video> object has some other id.
As the video element call.remoteVideo used to display the received video stream is in some browsers replaced with custom HTML elements you cannot set its width and height manually.
To resize the video element call.remoteVideo to other sizes than its initial size you must use call.SetVideoSize()
Property containing HTML5 <video> object.
document.getElementById("remoteVideo")
Usually you set call.remoteVideo in wrtc.onNewCall(). If you change it later you need to call wrtc.changeMedia() after.
wrtc.onNewCall = function(call) {
...
call.remoteVideo=document.getElementById("hisvideo");
...
};