How to finalize a DVD-R on Windows 10 so it will play on a standard DVD player?

Windows Movie Maker was officially discontinued by Microsoft and replaced by Video Editor  which is built in with Microsoft Photos on Windows 10, 

you can also try

https://apps.microsoft.com/detail/9mvfq4lmz6c9?hl=en-US&gl=US

Going retro huh?

Sure, it's cool to make a DVD that actually plays in a real Standalone DVD-Player in the living-room.

Firstly, yes use DVD-R media as that is the most compatible for this purpose (and you won't have to change BookType). I suggest sticking with single-sided DVD-R discs (aka DVD5).

You should not try to use ImgBurn program any more (so, you will need a different authoring/burning program), but these are the settings you need:

Insert blank DVD-R
Open ImgBurn and switch to Build mode.
Ensure it's set to output to Device.
Notice Verify is checked.
Browse folders and Select the root folder (one that holds the DVD s VIDEO_TS and AUDIO_TS folders)
Press the Calculate icon to make sure it will fit. It should have a few megs of free space (at least)
Device Tab, Speed is usually safer at 8x for DVD5s and 2.4 for DVD9-DL
Options tab, choose ISO9660+UDF in the 'File System' drop down box.
- Defaults here are fine (UDF 1.02 and Recurse Subs)
Labels tab, and enter the same Volume label in both fields (ISO9660 and UDF) ... no spaces but _ is ok
Click main Build/Copy Icon to burn it.
The drive will open after burn, and close again to Verify.
Verify 99.9% guarantees a successful burn (if the source files were correct).

You could install CyberLink Media Suite Essentials for Dell (free) which should allow you to finalize a DVD.