One reason why these DVD's do not play is because they were made in an area that is NOT where you are.
The world is divided in to DVD regions from 0, plays anywhere, to 6. The numbers go up to 9 but for the sake of this post, 0 to 6 are the ones you should be interested in.
This link will give you more information on what regions different countries are in.
As these DVD's are not copy protected, I trust you, you can use Mac the Ripper to convert them all to region 0.
Save the files and burn them to DVD using Toast. They will now play in any DVD player.

Bye the way, the term Non-Booting usually applies to a CD/DVD that can be used to startup at computer as it contains a copy of the Operating System. This does not apply to what you are referring to.

P