I have an extra monitor here and I was wondering if there was an adapter that would alow me to shoot a video signal in there like the yellow connector?
By yellow connector do you mean the yellow cable on the composite cables? IE the red/white/yellow cable?
If you do, as far as I know you can't use a simple adapter to go from VGA to composite video. There are a few PC-to-TV video devices that will do that for you as well as some video cards, either way it will cost you upwards of $70USD. To find some go to any home/PC electronics vendor's site and search for PC to TV, should bring up a list of those things.
If you want to do it without a computer then you will need one of those PC-to-TV devices I mentioned earlier. They work like this: you plug the VGA cable into the PC-to-TV device, then run a composite cable from the PC-to-TV device into whatever device you are getting your video signal from (IE a DVD player or Playstation).