I use DVD Decrypter and DVD Shrink (Nero Burn) to back-up dvds, but the dvds wont play in anything except my computer. Apparently they didn't finalize. Does anyone know an easy way of doing this?

your dvd player may not be able to read the DVD+r disks properly.

go back to nero and set the booktype to dvd-rom for compatibility and burn it again (untick the "add files at later sessions" to finalize it when burning.