after burning a dvd it won't play on my dvd player only on my computer

I was about to say that if you just burnt a DVD with some .MP4 files on it, there would be nothing in the DVD-Video standard requiring any particular set-top DVD player to play the disc. Many DVD players will play "loose" files, but that's just an additional capability that has become common on newer players. Not one that every player has.

But if there's a [.VIDEO_TS] directory with a .VOB inside, that sounds like you ran some authoring application that took the trouble to convert the video to MPEG-2 format and put it where a DVD player would expect to find it.

Make sure the DVD media and format used is compatible with the DVD media formats supported by the DVD player.

In the before times of the optical era, DVD+R and DVD+RW media will not work in a DVD-R or DVD-RW drive, for instance. It should work in a DVD+R/DVD+RW drive, or in a so-called quad-format (DVD+R/DVD+RW/DVD-R/DVD-RW, occasionally maybe also with DVD-RAM) DVD drive.

Some DVD players can be fussy about the recording format used, too: there are commercial snd open-source DVD authoring tools available.

If this is an old DVD player, here is an old description of how those work: https://www.linux.com/news/quick-guide-dvd-authoring/

It sounds as if a file recognizable only to a computer was burnt or copied to the DVD. Can you open the DVD and see if it has a Video_TS folder in it?

I'm not familiar with either app. I use Toast mainly to burn DVD's. Have you tried to play the DVD on a different DVD player? If it doesn't work there then I would suspect your burning app is at fault. The content of the DVD you ripped was your own, not a commercial DVD? DRM could be interfering with the copying.

But what app does it open to play the DVD, DVD Player or something else such as VLC ? Logically thinking if the computer can open and play the DVD with DVD Player(part of the OS)then it should work on a commercial player. As I said before, why don't you try another burn app? The one MrHoffman gave you the link would be a good place to start. It is free.

Might try Burn.app...

https://burn-osx.sourceforge.io/Pages/English/home.html

How did you copy dvd to the mini, then what app did you use to burn the dvd with?

Exactly as Servant of Cats says. As Mr.Hoffman suggested, why not try a different burn app?

mp4 should be the file of choice.

Out of curiosity what app do you play the DVD on your computer with?