Minimal MediaPlayer

activity_main.xml

<?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:layout_margin="16dp"
    android:orientation="vertical"
    tools:context="com.example.myapplication.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />

    <SurfaceView
        android:id="@+id/a_main_surface"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

AndroidManifest.xml

<uses-permission android:name="android.permission.INTERNET" />

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private static final String VIDEO_URL = "http://techslides.com/demos/sample-videos/small.mp4";

    private SurfaceView surfaceView;
    private SurfaceHolder surfaceHolder;

    private MediaPlayer mediaPlayer;

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

        surfaceView = (SurfaceView) findViewById(R.id.a_main_surface);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder surfaceHolder) {
                mediaPlayer = MediaPlayer.create(MainActivity.this, Uri.parse(VIDEO_URL));
                mediaPlayer.setDisplay(surfaceHolder);
                mediaPlayer.start();
            }

            @Override
            public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {

            }

            @Override
            public void surfaceDestroyed(SurfaceHolder surfaceHolder) {

            }
        });
    }
}