I'm not familiar with the Movies on CD/DVD interface. Yet I think there must be an "Finish movie", "Burn movie" or "Export project" option anywhere on the interface. Could you please verify this? If you find such a button, I think by clickung on that button you'll see the option to burn on Blu Ray of Dvd disc.
Yet I also know that sometimes it's not the program that causes the problem, but the disc one uses. Make therefore sure that you use reliable quality discs.
Another issue you might consider, is whether your burningsettings are set properly. You might try to watch the introduction tutorial on the magix-site first to see the users basics.
Use DVD+RW rewriteable discs until you have got what you want then burn to DVD.
If all else fails locate the DVD image folder which contains the VOBs etc and try burning these to video DVD using different burnng software if you have one.