A sample project to explain this issue clear.https://code.google.com/p/android/issues/detail?id=192551&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars

KeySensitiveSeekBar.java

import android.content.Context;
import android.util.AttributeSet;
import android.view.KeyEvent;
import android.widget.SeekBar;

/**
 * This is workaround version for SeekBar which didn't detect the progress changed
 * by arrow key pressed.
 *
 */
public class KeySensitiveSeekBar extends SeekBar {
    private OnKeyProgressChangeListener mOnKeyProgressChangeListener;

    public KeySensitiveSeekBar(Context context) {
        super(context);
    }

    public KeySensitiveSeekBar(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public KeySensitiveSeekBar(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (isEnabled()) {
            int increment = getKeyProgressIncrement();
            switch (keyCode) {
                case KeyEvent.KEYCODE_DPAD_LEFT:
                    increment = -increment;
                    // fallthrough
                case KeyEvent.KEYCODE_DPAD_RIGHT:
                    // Let progress bar handle clamping values.
                    setProgress(getProgress() + increment);
                    onKeyChange();
                    return true;
            }
        }
        return true;
    }

    /**
     * A hook method for arrow key pressed.
     */
    protected void onKeyChange() {
        if (mOnKeyProgressChangeListener != null) {
            mOnKeyProgressChangeListener.onKeyProgressChange(this);
        }
    }

    public void setOnKeyProgressChangeListener(OnKeyProgressChangeListener listener) {
        mOnKeyProgressChangeListener = listener;
    }

    /**
     * A callback to indicate the progress changed by arrow key pressed.
     */
    public interface OnKeyProgressChangeListener {
        void onKeyProgressChange(SeekBar seekBar);
    }
}

MediaController.java

public class MediaController extends FrameLayout implements OnClickListener {
    private ImageButton mPlayButton;
    private TextView mCurrentTime;
    private TextView mTotalTime;
    private KeySensitiveSeekBar mSeekBar;
    private IMediaPlayer mPlayer;
    private SimpleDateFormat mDateFormat;

    private static final int SHOW_PROGRESS = 0;
    private static final int SEEK_BY_USER = 1;
    private static final int PLAY_AGAIN = 2;

    public MediaController(Context context) {
        super(context);
        initialize(context);
    }

    public MediaController(Context context, AttributeSet attrs) {
        super(context, attrs);
        initialize(context);
    }

    public MediaController(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initialize(context);
    }

    private void initialize(Context context) {
        LayoutInflater layoutInflater = LayoutInflater.from(context);
        layoutInflater.inflate(R.layout.layout_media_controller, this, true);

        mPlayButton = (ImageButton) findViewById(R.id.video_play_btn);
        mPlayButton.setOnClickListener(this);
        mCurrentTime = (TextView) findViewById(R.id.video_current_time);
        mTotalTime = (TextView) findViewById(R.id.video_total_time);
        mSeekBar = (KeySensitiveSeekBar) findViewById(R.id.video_seek_bar);
        mSeekBar.setOnSeekBarChangeListener(mOnSeekBarChangeListener);
        mSeekBar.setOnKeyProgressChangeListener(mOnKeyProgressChangeListener);
        mDateFormat = new SimpleDateFormat("mm:ss");
    }

    public void setMediaPlayer(IMediaPlayer mediaPlayer) {
        mPlayer = mediaPlayer;
    }

    private Handler mSeekBarHandler = new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(Message msg) {
            int progress;
            switch (msg.what) {
                case SHOW_PROGRESS:
                    // show progress...
                    break;

                case SEEK_BY_USER:
                    //Seek by user...
                    break;

                case PLAY_AGAIN:
                    //Play again...
                    break;
            }
            return true;
        }
    });

    private final OnSeekBarChangeListener mOnSeekBarChangeListener = new OnSeekBarChangeListener() {

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            mSeekBarHandler.sendEmptyMessage(SHOW_PROGRESS);
            if (mPlayer != null) {
                mPlayer.seekTo(seekBar.getProgress());
            }
            mSeekBarHandler.sendEmptyMessage(SEEK_BY_USER);
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {
            mSeekBarHandler.removeMessages(SHOW_PROGRESS);
        }

        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            if (fromUser) {
                mPlayer.seekTo(progress);
                mSeekBarHandler.sendEmptyMessage(SEEK_BY_USER);
            }
        }
    };

    private final OnKeyProgressChangeListener mOnKeyProgressChangeListener = new OnKeyProgressChangeListener() {
        @Override
        public void onKeyProgressChange(SeekBar seekBar) {
            if (mOnSeekBarChangeListener != null) {
                mOnSeekBarChangeListener.onProgressChanged(seekBar, seekBar.getProgress(), true);
            }
        }
    };
    
    //Other methods omitted...

    public interface IMediaPlayer {

        void start();

        void pause();

        int getDuration();

        int getCurrentPosition();

        void seekTo(int pos);

        boolean isPlaying();

        void progressCallback(int progress);
    }

}

KeySensitiveSeekBar and MediaController is my sample project.KeySensitiveSeekBar is my workaround solution to explain the problem. 😄