如何在全屏幕上制作YouTube视频？

Question

我为我的网站kino-films.com创建应用程序。但视频无法以全屏模式播放？请帮帮我。我使用说明书完成了申请：https://www.youtube.com/watch?v=a5dlmqM9Oo8 第三天，我无法解决问题，请帮帮我。感谢

ACTIVE MAIN.XML

 <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.kino_films.uzbekkino.MainActivity">

    <WebView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_centerHorizontal="true"
        android:id="@+id/webView" />
</RelativeLayout>

主要活动.JAVA

package com.kino_films.uzbekkino;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {
    private WebView mywebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mywebView = (WebView)findViewById(R.id.webView);
        WebSettings webSettings = mywebView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        mywebView.loadUrl("http://kino-films.com");
        mywebView.setWebViewClient(new WebViewClient());
    }

    @Override
    public void onBackPressed() {
        if(mywebView.canGoBack()) {
            mywebView.goBack();
        } else {
            super.onBackPressed();
        }

    }
}

ANDROID MANIFEST

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.kino_films.uzbekkino">
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>