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
https://www.microsoft.com/en-us/software-download/windows10
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
OR
USB Thumb Drive.... I use Rufus
http://rufus.akeo.ie/