Maybe changing the media event type will work more consistently?

player.js

@@ -65,7 +65,7 @@ function init() {
             var loaded = 0
             var streams = document.querySelectorAll('video')
             streams.forEach(function(stream) {
-                stream.addEventListener('loadedmetadata', function(event) {
+                stream.addEventListener('canplay', function(event) {
                     loaded += 1
                     if(loaded === streams.length) {
                         callback()}})})