Although I'm not a big fan of the media creation tool, I'm pretty sure that it supports DVD creation.
Have a read under the section
Using the tool to create installation media (USB flash drive, DVD, or ISO file) to install Windows 10 on a different PC (click to show more or less information)
Follow these steps to create installation media (USB flash drive or DVD) you can use to install a new copy of Windows 10, perform a clean installation, or reinstall Windows 10.
The one possible caveat being
When burning a DVD from an ISO file, if you are told the disc image file is too large you will need to use Dual Layer (DL) DVD Media
At least with that as a resource you can be reasonably certain that your media contains the latest version available. I don't know when you acquired you current "bootable Win 10 flash drive", but it may have an older version.
I generally prefer to keep a recent version of the ISO saved on my computer and when I need to create bootable media
DVD.... I use ImgBurn http://imgburn.com/index.php?act=download
USB Thumb Drive.... I use Rufus http://rufus.akeo.ie/