Hi Mitch

I think you will find most pc monitors will not accept composite video ( the kind your dvd player has coming out of the back on RCA phono jacks).

I suspect you have misinterpreted catalogue listings, most VGA to BNC cables just split out the RGB and sync onto four or five plugs to facilitate the connection to older monitors or high end pro AV kit, and plugging phono adaptors into them would just give you four or five phonos each with a different signal on them.

Check out the specs. of your monitor by reading the manual or contacting the manufacturers before you spend any money.

You may be lucky - if your monitor has a SVHS socket then you should be able to plug that straight into your dvd player.