I have a Pioneer PDP-503CMX plasma monitor with BNC-V(G,B,R,HD,VD) component video input. How do I connect DVD player that has 3 RCA component Video out.
You need to look in you ownders manual. I would image that the Pioneer could take a component input to its RGB+Horizontal/Verticle Sync (the jacks you mention) BUT you must find a way to tell the TV that it is receiving a component signal and not an RGB+HV signal. There will be a switch of the TV or a menu item in the setup.
Usually this is not the case because Component and RGB ar totally incompatable, but Pioneer is the type of that would allow it. You will need some $3 BNC to RCA adapters from Radio Shack though for the connections and you will be using the Reg, Green and Blue jacks only.