Meanwhile I decided I could not wait. I also wrote a script to do exactly that. If you want to use it, save it as a bookmarklet, and when on a OGS review page, if you click it, it will toggle the Play Controls area on or off (click again to undo).
javascript:(function(){ var a = document.getElementsByClassName('PlayControls')[0]; if( a.style.display == 'none' ) {a.style.display = ''; } else { a.style.display = 'none' }})();