An empty checkbox icon <imgsrc="assets/icon-unseen.png?raw=true"alt="unseen icon"width="20px"style="margin:0 5px;"> will show for videos you haven't marked as watched. Click on it and the icon will change to a filled checkbox <imgsrc="assets/icon-seen.png?raw=true"alt="seen icon"width="20px"style="margin:0 5px;"> indicating it as watched.
When available the <imgsrc="assets/icon-gridview.png?raw=true"alt="gridview icon"width="20px"style="margin:0 5px;"> gridview icon will display the list in a grid, the <imgsrc="assets/icon-listview.png?raw=true"alt="listview icon"width="20px"style="margin:0 5px;"> listview icon will arrange the items in a list.