강의 내용과 틀림

class MainActivity 

package kr.co.dothome.braverokmc.tutorial72;

import android.os.Bundle;
import android.widget.Toast;

import com.google.android.youtube.player.YouTubeBaseActivity;
import com.google.android.youtube.player.YouTubeInitializationResult;
import com.google.android.youtube.player.YouTubePlayer;
import com.google.android.youtube.player.YouTubePlayerView;



public class MainActivity  extends YouTubeBaseActivity implements YouTubePlayer.OnInitializedListener {

    public static final String API_KEY = "AIzaSyAtpVA1OTj-ulVDGvNGeKS93QsBYpK0HC4";

    //https://www.youtube.com/watch?v=<VIDEO_ID>
    public static final String VIDEO_ID = "vewH-f3fAes";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        // Initializing YouTube player view
        YouTubePlayerView youTubePlayerView = (YouTubePlayerView) findViewById(R.id.youtube_player_view);
        youTubePlayerView.initialize(API_KEY, this);
    }


    @Override
    public void onInitializationFailure(YouTubePlayer.Provider provider, YouTubeInitializationResult result) {
        Toast.makeText(this, "Failed to initialize.", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onInitializationSuccess(YouTubePlayer.Provider provider, YouTubePlayer player, boolean wasRestored) {
        if(null== player) return;

        // Start buffering
        if (!wasRestored) {
            player.cueVideo(VIDEO_ID);
        }


        // Add listeners to YouTubePlayer instance
        player.setPlayerStateChangeListener(new YouTubePlayer.PlayerStateChangeListener() {
            @Override
            public void onAdStarted() { }

            @Override
            public void onError(YouTubePlayer.ErrorReason arg0) { }

            @Override
            public void onLoaded(String arg0) { }

            @Override
            public void onLoading() { }

            @Override
            public void onVideoEnded() { }

            @Override
            public void onVideoStarted() { }
        });


        player.setPlaybackEventListener(new YouTubePlayer.PlaybackEventListener() {
            @Override
            public void onBuffering(boolean arg0) { }

            @Override
            public void onPaused() { }

            @Override
            public void onPlaying() { }

            @Override
            public void onSeekTo(int arg0) { }

            @Override
            public void onStopped() { }
        });
    }






}

R.layout.activity_main

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >

    <com.google.android.youtube.player.YouTubePlayerView
        android:id="@+id/youtube_player_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>






</LinearLayout>

class YouTubePlayerFragmentActivity

package kr.co.dothome.braverokmc.tutorial72;

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.widget.Toast;

import com.google.android.youtube.player.YouTubeBaseActivity;
import com.google.android.youtube.player.YouTubeInitializationResult;
import com.google.android.youtube.player.YouTubePlayer;
import com.google.android.youtube.player.YouTubePlayerFragment;

/**
 * Created by choi on 2017-04-25.
 */

public class YouTubePlayerFragmentActivity extends YouTubeBaseActivity {
   public static final String API_KEY = "AIzaSyAtpVA1OTj-ulVDGvNGeKS93QsBYpK0HC4";

    //https://www.youtube.com/watch?v=<VIDEO_ID>
    public static final String VIDEO_ID = "vewH-f3fAes";

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_youtube_player_fragment);

        //Initializing and adding YouTubePlayerFragment
        FragmentManager fm = getFragmentManager();
        String tag = YouTubePlayerFragment.class.getSimpleName();
        YouTubePlayerFragment playerFragment = (YouTubePlayerFragment) fm.findFragmentByTag(tag);
        if (playerFragment == null) {
            FragmentTransaction ft = fm.beginTransaction();
            playerFragment = YouTubePlayerFragment.newInstance();
            ft.add(android.R.id.content, playerFragment, tag);
            ft.commit();
        }

        playerFragment.initialize(API_KEY, new YouTubePlayer.OnInitializedListener() {
            @Override
            public void onInitializationSuccess(YouTubePlayer.Provider provider, YouTubePlayer youTubePlayer,
                                                boolean b) {
                youTubePlayer.cueVideo(VIDEO_ID);
            }

            @Override
            public void onInitializationFailure(YouTubePlayer.Provider provider,
                                                YouTubeInitializationResult youTubeInitializationResult) {
                Toast.makeText(YouTubePlayerFragmentActivity.this, "Error while initializing YouTubePlayer.", Toast.LENGTH_SHORT).show();
            }
        });
    }


}

R.layout.activity_youtube_player_fragment

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/content"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</FrameLayout>