Why can't I set text to an Android TextView?

The code should instead be something like this:

TextView text = (TextView) findViewById(R.id.this_is_the_id_of_textview);
text.setText("test");

You set the text to a field that was rendered in another instance of your activity residing in cash,say when it was landscape oriented. Then it was recreated due to some reason. You need to set the text in an unusual way by saving the string to SharedPreferences and force relaunch the activity using recreate(), say for mOutputText:

@Override
protected void onResume() {
    super.onResume();
    String sLcl=mPreferences.getString("response","");
    if(!sLcl.isEmpty()){
        mOutputText.setText(sLcl);
        mPreferences.edit().putString("response","").commit();
    }
}

private void changeText() {
    mPreferences.edit().putString("response",responseText).commit();
    recreate();
}
@Override
protected void onActivityResult(
        int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
        case CAPTURE_MEDIA_RESULT_CODE:
            if (null == data || null == data.getData()) {
               showMessage("Sorry. You didn't save any video");
            } else {
                videoUri = data.getData();
                mProgress = new ProgressDialog(this);
                mProgress.setMessage("Uploading onYoutube ...");

                authorizeIt();// SAY YOU CALL THE changeText() at the end of this method
            }
            break;
    }
}