Create StageWebView instance and load video:

var webView:StageWebView = new StageWebView();
var path:String = 'file://path_to_video/video.mp4';
webView.stage = this.stage;
webView.viewPort = new Rectangle( x, y, width, height);
webView.loadURL(path);

Dispose and remove:

webView.reload();
webView.viewPort = null;
webView.dispose();
webView = null;