VGA means nothing more than "it's not EGA/CGA". Without knowing exactly what the timings are, it's hard to say what the other device will do.
Essentially Y Pr Pb refers to a colorspace and how it's encoded. The rest is up in the air.
Flat screen means TV? A TV would either work in 15KHz or if you're lucky it accepts scan doubled video.
I'd guess that the cable is meant to work with a certain video card that converts the color space internally and provides the proper timings for a TV.
Also, in 2000, there where hardware MPEG decoders to play back video, and that HD-15 connector might not refer to a VGA video card at all.
Out of the box, VGA is non-interlaced, old-school TV video is interlaced, it will not interconnect without scan doubling hardware, which requires much more than a handful of gates and opamps.
Something else is going on here. You can not go from VGA to video "passively" unless the video card has specific hardware to do so.