The simple answer took a little Googling.
Windows Movie Maker that comes with Windows 8 no longer includes Windows DVD Maker.
I don't know if you could copy DVDMaker.exe for a Vista or Windows 7 OS & use it or not.
Or maybe copy the complete MovieMaker for a Windows 7 Program Files & paste it in your Windows 8 Program files.
Sometimes that works & sometimes it doesn't . I don;t have Windows 8 to test that with.
If you go that route be sure to save the Windows 8 Movie Maker folder from Program Files somewhere else on your OS . Just in case it doesn't work.
Or rename the Windows 7 one something like MovieMakerW7 & paste that in your Program Files. Then just create a shortcut to MOVIEMK.exe in that folder.
The worst that will happen is it won't work & you can just delete it.