Renames videocontainer overlay to hoverOverlay.

css/_videolayout_default.scss

     height: $thumbnailIndicatorSize + $toolbarPadding;
 }
 
-.videocontainer__overlay {
+.videocontainer__hoverOverlay {
     position: relative;
     width: 100%;
     height: 100%;

index.html

                     <audio id="localAudio" autoplay muted></audio>
                     <div class="videocontainer__toolbar"></div>
                     <div class="videocontainer__toptoolbar"></div>
-                    <div class="videocontainer__overlay"></div>
+                    <div class="videocontainer__hoverOverlay"></div>
                 </span>
                 <audio id="userJoined" src="sounds/joined.wav" preload="auto"></audio>
                 <audio id="userLeft" src="sounds/left.wav" preload="auto"></audio>

modules/UI/videolayout/RemoteVideo.js

     container.appendChild(toolbar);
 
     let overlay = document.createElement('div');
-    overlay.className = "videocontainer__overlay";
+    overlay.className = "videocontainer__hoverOverlay";
     container.appendChild(overlay);
 
     var remotes = document.getElementById('remoteVideos');

modules/UI/videolayout/SmallVideo.js

     // show hide overlay when there is a video or avatar under
     // the display name
     UIUtil.setVisibility(   $('#' + this.videoSpanId
-                                + ' .videocontainer__overlay'),
+                                + ' .videocontainer__hoverOverlay'),
                             (displayMode === DISPLAY_AVATAR_WITH_NAME
                                 || displayMode === DISPLAY_VIDEO_WITH_NAME));
 };