How to exit fullscreen video on iOS CNA (Captive Network Assistant)

Question

I'm trying to optimize UX in a WiFi Captive Portal at work and I want video to close at end.

Problem is: The browser where video plays is the iOS CNA, that apparently has no support to *EndFullScreen() method, so it's not a possible solution.

I've have this code that identifies when video ends:

iphone_video.addEventListener('ended', function() {
  // here should go endfullscreen code;
}, false);