The official developer of the application created a tutorial page that can be visited by users. On the page you will find the correct steps you have to take in order to export a video. There is also a burning instruction posted at the bottom of the website.
Access the page using the following URL: http://www.videosoftdev.com/how-to-export-project
Based on my experience concerning these kinds of apps, I would recommend changing the export settings by yourself instead of using the predefined ones.