private void processButtonAction() {
        if (currentFile != null) {
            if (!currentFile.exists()) {
                text.append("Can't process not-existing file: " + currentFile.getAbsolutePath());
                return;
            }

            text.append(String.format(
                "Started to process file: %s.%s",
                currentFile.getAbsolutePath(),
                newline)
            );

            mediator.startVideoProcessing(currentFile);
            this.setStateProcessing();
            return;
        }

        if (!url.equals("")) //URL contains http://
        {
            //validation of URL is needed (also if URL exists)
            text.append(String.format("URL is not supported right now."));
            this.setStateInitial();
        }
    }