YouTube embed player not working in Javascript

Question

Since a couple of days, code which worked fine to embed a YouTube video via Javascript stopped working. Now the video loads but it is not playable (the play button is not clickable), with this error in the console:

Uncaught TypeError: a.g.mX is not a function
at O_ (https://www.youtube.com/yts/jsbin/player-en_US-vfl8LqiZp/base.js:3796:24)
at new P_ (https://www.youtube.com/yts/jsbin/player-en_US-vfl8LqiZp/base.js:3791:111)
at new c2 (https://www.youtube.com/yts/jsbin/player-en_US-vfl8LqiZp/base.js:3985:268)
at new i2 (https://www.youtube.com/yts/jsbin/player-en_US-vfl8LqiZp/base.js:4005:210)
at i2.create (https://www.youtube.com/yts/jsbin/player-en_US-vfl8LqiZp/base.js:6950:321)
at zh.<anonymous> (https://www.youtube.com/yts/jsbin/www-embed-player-vflxTxlSH/www-embed-player.js:428:269)
at zh.k.lb (https://www.youtube.com/yts/jsbin/www-embed-player-vflxTxlSH/www-embed-player.js:428:308)
at Dh (https://www.youtube.com/yts/jsbin/www-embed-player-vflxTxlSH/www-embed-player.js:426:143)
at zh.k.pa (https://www.youtube.com/yts/jsbin/www-embed-player-vflxTxlSH/www-embed-player.js:419:176)
at https://www.youtube.com/yts/jsbin/www-embed-player-vflxTxlSH/www-embed-player.js:461:420

The JS code is as follows:

document.getElementById('player').setAttribute("style","height:"+(window.innerHeight * 0.87)+"px;");
document.getElementById('youtube_frame').src="http://www.youtube.com/player_api";
    var player;
    function onYouTubePlayerAPIReady() {
            player = new YT.Player('player', {
              height: "100%",
              width: "100%",
              videoId: start_video,
              events: {
                'onReady': onPlayerReady,
                'onStateChange': onPlayerStateChange
              }
            });
    }
    function onPlayerReady(event) {

            player_ref = event.target;
            event.target.playVideo();
        }

        // when video ends
        function onPlayerStateChange(event) {        
            if(event.data === 0) {          

                event.target.loadVideoById(start_video);
            }
        }

Playback also broke on another prototype that I run. Everything used to work fine until a couple of days ago. I cannot find anything online, perhaps someone can shed some light?

----- UPDATE ----

Embedding playback is broken again:

Uncaught TypeError: a.g.setActionHandler is not a function
at M_ (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3788:24)
at new N_ (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3783:111)
at new a2 (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3978:367)
at new g2 (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3999:210)
at g2.create (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:6995:333)
at Gi.<anonymous> (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:507:269)
at Gi.l.jb (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:507:308)
at Ki (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:505:143)
at Gi.l.oa (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:498:176)
at https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:557:378

Answer 1

The issue has been resolved by Google and now YouTube videos play ok!

Wonder what happened?

----- UPDATE 23/02/2017 ------

Embedding playback is broken again:

Uncaught TypeError: a.g.setActionHandler is not a function
at M_ (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3788:24)
at new N_ (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3783:111)
at new a2 (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3978:367)
at new g2 (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:3999:210)
at g2.create (https://www.youtube.com/yts/jsbin/player-en_US-vflqOi6vK/base.js:6995:333)
at Gi.<anonymous> (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:507:269)
at Gi.l.jb (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:507:308)
at Ki (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:505:143)
at Gi.l.oa (https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:498:176)
at https://www.youtube.com/yts/jsbin/www-embed-player-vfl-i_LLs/www-embed-player.js:557:378

Answer 2

I have this problem in Chrome 56.0.2924.87 (64-bit) when "experimental functions" are enabled.

base.js:7046 Uncaught TypeError: a.g.setActionHandler is not a function
at bY (https://www.youtube.com/yts/jsbin/player-ru_RU-vfleBND20/base.js:3618:24)
at new cY (https://www.youtube.com/yts/jsbin/player-ru_RU-vfleBND20/base.js:3613:111)
at new z1 (https://www.youtube.com/yts/jsbin/player-ru_RU-vfleBND20/base.js:3983:268)
at new j2 (https://www.youtube.com/yts/jsbin/player-ru_RU-vfleBND20/base.js:4044:209)
at Object.j2.create (https://www.youtube.com/yts/jsbin/player-ru_RU-vfleBND20/base.js:7045:317)
at Object.ytplayer.load (https://www.youtube.com/watch?v=n-AdoTkXwbc:241:75024)
at https://www.youtube.com/watch?v=n-AdoTkXwbc:241:75172
at https://www.youtube.com/watch?v=n-AdoTkXwbc:241:75181

We can disable this option here: chrome://flags/#enable-experimental-web-platform-features

-- UPDATE 10.03.2017 --

Chrome 57.0.2987.98 (64-bit) is published today and works fine!