Composite Video out of a converter box is only capable with CGA monitor and only if the CGA monitor has a composite input. Of course most CGA monitors are long gone. For a while when they became obsolete with the first VGAs, you could buy them dirt cheap out of catalogs and hook them to the output of a VCR and you have a TV and VCR. VCRs were also cheap as people trashed them for any reason and where easy to fix. Basically the old CGA standard was
NTSC.
Seems to me for all that money to convert, it would be just a cheap to buy a good USB or Tuner card for the computer, then you would also have a
DVR.