MP4 doesn't play in Video Component in Animate 2020

I've been doing some more debugging and think that this issue may be due to the change in CreateJS's MovieClip.added event behavior.

In v19, the added() event handler is called for every frame which updates $this,_lastAddedFrame to the current frame.  In v20, the added() event handler is only called on frame 0.

(lib.an_Video = function(options) {
    this._element = new $.an.Video(options);
    this._el = this._element.create();
    var $this = this;
    this.addEventListener('added', function() {
        $this._lastAddedFrame = $this.parent.currentFrame;
        $this._element.attach($('#dom_overlay_container'));
});
}).prototype = p = new cjs.MovieClip();

The this._lastAddedFrame is then checked in the _updateVisibility() function.  If the this._lastAddedFrame is not equal to the currentFrame, then the video element is detached (aka removed from the DOM).

function _updateVisibility(evt) {
    if((this.getStage() == null || this._off || this._lastAddedFrame != this.parent.currentFrame) && this._element) {
        this._element.detach();
        stage.removeEventListener('drawstart', this._updateVisibilityCbk);
        this._updateVisibilityCbk = false;
    }
}