How to change videos / update videos on a textureView on android

Question

I have successfully played a video using MediaPlayer on TextureView, now I am trying to program so that the video automatically changes after a certain frame is passed. However, after a certain condition is met, I am unable to update the video. It is stuck at the first video(the last frame before the condition is met).

How do I load a new video and start playing once the first video is passed a certain frame? Here is what I have, I use a CountDownTimer for getting the most accurate current time.

public class PreviewVideo extends AppCompatActivity implements TextureView.SurfaceTextureListener {
    TextureView textureView;
    MediaPlayer videoMedia;
    Boolean pastFrame=false;
    int currentTime;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_preview_video);

        textureView = (TextureView) findViewById(R.id.previewVideo);
        textureView.setSurfaceTextureListener(this);

        }

    @Override
    public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
        surf=new Surface(surface);
        videoMedia=new MediaPlayer();
        videoMedia.setSurface(surf);

        try{
            if (!pastFrame){
                 videoMedia.setDataSource(this,firstUri);
            }
            else {
                 videoMedia.setDataSource(this,secondUri);
            }
            videoMedia.prepare();
            playListeners();

        } catch(IOException e){e.printStackTrace(); }


    }

    private void playListeners() {
          count=new CountDownTimer(videoMedia.getDuration()*10, 1){
            @Override
            public void onTick(long l)
            {
                currentTime=videoMedia.getCurrentPosition();
                if (currentTime>=setFrame && pastFrame==false){
                textureView.setSurfaceTextureListener(this);//Do I call this again??
                pastFrame=true;
                }
            @Override
            public void onFinish(){

            }
        }.start();         
    }


}