private void PrepareCompleted()
    {
        stateText.text = "PrepareCompleted";
        Debug.Log("PrepareCompleted");

        if (logoVideo.State == Art.Sample.VideoPlay.PlayState.Loaded &&
            opVideo.State == Art.Sample.VideoPlay.PlayState.Loaded)
        {
            logoVideo.PlayPrepared(false, false);
        }
    }
    private void PlayEnd()
    {
        stateText.text = "PlayEnd";
        Debug.Log("PlayEnd");

        if (logoVideo.State == Art.Sample.VideoPlay.PlayState.Stoped &&
            opVideo.State == Art.Sample.VideoPlay.PlayState.Loaded)
        {
            buttonText.text = "Stop";
            logoVideo.SetEnabled(false);
            button.interactable = false;
            opVideo.PlayPrepared(false, true);
        }
        else if (opVideo.State == Art.Sample.VideoPlay.PlayState.Stoped)
        {
            buttonText.text = "Play";
            opVideo.SetEnabled(false);
            button.interactable = true;
        }
    }